I always wondered why Hagrid never told Harry how to get onto the platform. Well perhaps it was because he knew that Petunia Dursley knew how, and expected her to explain to Harry how to walk through the barrier. In HP and the Deathly Hallows, inside Snape's memory, Petunia was with Lily and their parents on platform 9 3/4. So she obviously knew how to get there. So, why not explain or tell Harry how? In HP and the Sorceror's Stone, Uncle Vernon asks where the school is. Harry checks his ticket and it doesn't say what part of the country, it just says to take the train at 11 o'clock on platform 9 3/4. Petunia was in the room while he tells them this. So she never explained to Harry. Why? Because she's always denying she knows anything about the magical world? Or was she just being crude?

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    I think she had no interest in helping out harry in any way. Surely not with anything related to magic
    – Vishwa
    Commented Feb 6, 2018 at 9:49
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    I think the better question is why Hagrid didn't explain it to Harry. Though the obvious answer is that he just forgot to tell him about it.
    – David K
    Commented Feb 6, 2018 at 13:24
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    did you mean cruel at the end there rather than crude?
    – Chris
    Commented Feb 6, 2018 at 19:31
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    Why would she? She detests the magic world because it got Lily killed (among other reasons). She does not particularly like Harry.
    – Polygnome
    Commented Feb 6, 2018 at 21:34
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    Occam's razor suggests that it's just a screenwriter's mistake. It's a fantasy movie, not real life, it doesn't have to be rational. Commented Feb 7, 2018 at 5:46

5 Answers 5


An additional possibility:

She did not think it would be a problem

After all, she had been there, and presumably she got on without a problem, because somebody was waiting for them or because they were guided. She had no reason to think it would be different for Harry.

This combines with all the other reasons (unwillingness to reveal she knows anything in front of Vernon, unwillingness to help, simple unwillingness to intervene, or simple ignorance or forgetfulness of the method to be used together with a reluctance of saying something incorrect).

In fact, I would say that she has no reason at all to tell Harry.

  • Except for him to get through the doorway? Surely... If she was taken through by her parents or sister and she's Harry's guardian. She, surely, had reason to tell Harry
    – Edlothiad
    Commented Feb 7, 2018 at 9:04
  • @Edlothiad What would that reason be? See it from her point of view: he's got a ticket, he may be wondering what the 9 3/4 means but he'll go there and find out and get on the platform just as Petunia did so long ago -- why intervene?
    – Law29
    Commented Feb 7, 2018 at 9:27
  • You're assumption is that Petunia finding it on her own, rather than having help be it from her parents or from outside, where as from what we're told, Harry is provided no help. there is clearly a reason not to tell Harry, as opposed to "why should I"
    – Edlothiad
    Commented Feb 7, 2018 at 9:31
  • Ahem, in the books, the Dursleys saw his confusion and were laughing at him, saying something like “good luck with your freaks” before leaving. It’s quite clear that she knew that it was a problem for Harry and was not helping, intentionally (And I assume that we’re talking about the books, as only in the books it’s revealed that Petunia ever was on platform 9¾).
    – Holger
    Commented Sep 27, 2023 at 12:27

I can think of a few possibilities:

  1. She'd forgotten.

    The simplest explanation of all. The time(s) she went there with Lily were decades ago, and part of a section of her life which she'd done her best to forget and excise from her memory. The woman who Harry grows up with isn't the same person as the girl who wanted to be able to do magic like her sister. Perhaps she's blotted out all of that part of her life.

  2. She didn't want to reveal any knowledge of the wizarding world.

    Especially in front of her suffocatingly Muggle husband. I doubt she ever told him that she'd once longed to be able to get into Hogwarts. He seemed as shocked as Harry when she got the Howler in book 5. Surely she wouldn't want to mention in front of him, at this early stage, that she'd actually had more involvement with the magical world than she'd admitted. Even if she did remember, she might not want to reveal that fact.

  3. She's being petty and spiteful.

    Why would she want to help Harry out? Let him get stuck at King's Cross not knowing how to access the platform. Then maybe he won't be able to study at Hogwarts and will have to live a Muggle life like she'd always wanted him to. She's certainly not going to make it any easier for him to go off into the insane world that claimed her sister's life.

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    That's what I was thinking too. I doubt she would forget... As she remembers the dementor comment Snape made. (Which was even further in her memories then being on the platform)
    – Flitoangel
    Commented Feb 6, 2018 at 0:03
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    I'm not sure we can put her wizard-phobia down to Vernon, who presumably knows nothing of the wizard world (the first chapter of the books is about Vernon being surprised to see strange people in robes on the street, etc.). She knows about the wizarding world, but resents it. She's got strong opinions of wizards and witches as "the wrong sort of people". One of the books has a scene about the Dursleys waiting for a visit by the Weasleys, full of prejudice about their manners etc.
    – AJFaraday
    Commented Feb 6, 2018 at 14:03
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    3. She resents Harry and is just being petty or spiteful. I mean, they kept him in a cupboard, so they clearly dislike him. I know I wouldn't go out of my way to help someone I disliked to that extent, so it seems plausible she wouldn't either. Commented Feb 6, 2018 at 14:47
  • 4. Something changed in the 20 years between events. Commented Feb 7, 2018 at 0:41
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    @Roddy Thanks; I incorporated this into the answer.
    – Rand al'Thor
    Commented Feb 7, 2018 at 1:22

Petunia hates wizards and witches! She hates Hogwarts, and had, up until that time, tried to deny any knowledge of their existence.

They had already taken great pains to prevent Harry going to Hogwarts. They were terrified by Hagrid's visit and absolutely would not want to help Hagrid in any way.

Fear leads to anger, anger leads to hate, and that way, the dark side lies.

The Dursleys hate magic, they also hate Harry. She doesn't want Harry to become a wizard, or to help him prosper in any way.

However, they could easily abandon him at Kings Cross station, saying he has a train to catch, which he did, but keep him away from the wizarding world by keeping how to get to the platform from him.

It's all pretty clear from the outset.

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    Going a bit further, its quite possible she blamed the death of her sister on the whole "magic" thing, and thus wasn't going to lift a finger to help someone else get into it. In her mind, if he couldn't figure it out, she'd have done him a favor by not helping.
    – T.E.D.
    Commented Feb 6, 2018 at 15:11
  • @T.E.D. Interesting thought, but we do need to look at how she treats Harry. He's kept in a cupboard under the stairs, in spite of their spare bedroom. Dudley's second bedroom. These aren't the actions of someone who wants her nephew to prosper.
    – AJFaraday
    Commented Feb 6, 2018 at 15:50
  • I thought she hated magic because her sister was treated as sooo special as the family witch, wasn't she so special going to hogwarts, and it was sibling jealousy.
    – WendyG
    Commented Feb 7, 2018 at 9:23
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    @WendyLisaGibbons She certainly rants along those lines, she resents Lily for being treated better by her parents, she also hates having responsibility for Harry following Lily's death. Also, you know, her sister has been killed, she doesn't know the details, but she does know that it's a wizarding reason, and that if Lily hadn't gone to Hogwarts she'd probably be alive. Family relationships are complicated, but it's definitely possible to both love and hate as sibling.
    – AJFaraday
    Commented Feb 7, 2018 at 9:32

I'd add a fourth possibility to Rand al'Thor's answer.

  1. She never knew

She was on Platform 9 3/4, but that doesn't mean she knew how to get there, in the same way that being driven somewhere doesn't mean you have the knowledge to drive a car. She may have assumed other magic was at work beyond "run at it".

  • How do you propose she "didn't know" that running at it would let one pass through? Do you have any sources that might support this reasoning?
    – Edlothiad
    Commented Feb 6, 2018 at 13:34
  • I'm not sure this makes sense. She would have seen spells performed by witches and wizards on the platform, presumably with the tell-tale signs, wands and words. She must have entered the platform by running at the wall, without any spells being done there and then.
    – AJFaraday
    Commented Feb 6, 2018 at 13:35
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    She knew that running at it was necessary. But maybe she didn't know it was sufficient. For all she knew there may have been other magic at work.
    – jfowkes
    Commented Feb 6, 2018 at 13:36
  • Ok... but she wasn't driven there in a car. When you're in a car you can Daydream and if you are not driving be completely unaware of what road you take or where you're going. But she walked there she knew that the way to platforms 9 and 3/4 was to walk into the barrier between platforms 9 and 10. Unless she was blindfolded, she knew perfectly well how to get to the Hogwarts Express.... It's nothing at all like being driven somewhere I'm sorry.
    – Flitoangel
    Commented Sep 8, 2018 at 5:03

I think she didn't want Harry to get into the world of wizards. She was always afraid of magic and despised wizards.

  • Could it not be possible she didn't want Vernon to know about her sister?
    – Edlothiad
    Commented Feb 6, 2018 at 10:05
  • @Edlothiad He already knew, so I'd go with no, that's not a possibility. Commented Feb 6, 2018 at 13:28
  • @AnthonyGrist Ah yes, I recall that. Vernon had a great dislike for James if I recall correctly
    – Edlothiad
    Commented Feb 6, 2018 at 13:33

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