London with kids

If by the Harry Potter Park you mean the Warner Brothers Studio Tour, I think you’ll be unlikely to get tickets for March. It sells out WEEKS ahead, and you can’t just turn up.

Wow, that’s in a few weeks! As the previous poster noted some popular ticketed sites will be sold out. Theater is fun and there are many shows suitable for her age group. Your problem will be availability. Here is a site that has a listing https://www.londontheatre.co.uk/whats-on/calendar/mar but we always go to the specific theater website to purchase tickets.

Thanks.
I will have a look for a theatrical performance

Maybe a cruise up the River Thames or the London Zoo?

If the WB Harry Potter Studio tours are sold out, you can consider the London Walks Harry Potter which tours the most famous sites in London. Here is the link with the schedule: http://www.walks.com/popular-walks/harry-potter.

hey lekka
don't know how many days you will be in london but here's a few things to check out
b-bakery.com afternoon tea tour on the big red bus or tea party at the bahery.
jasons.co.uk london barge canal ride
visitlondon.com has lots of info for kids, also theatre tickets maybe a matinee show,
withlocals.com has things to do and some kid friendly that are free with an adult.
streetsensation.co.uk street markets around london
walks.com different walks on different days
stmartin-in-the-fields.org have lunch in their cafe in a crypt
maybe a train ride to brighton, boardwalk arcade about an hour away (visitbrighton.com)
we walked thru covent gardens, picadilly circus was fun to see the "free" entertainment, trafalgar square, ate fish and chips. lots of walking: wear comfy shoes. having a 9 year old may slow up things but just enjoy, hope she can compromise to see maybe what you want. have a great time enjoy
aloha

I plan on taking my children next year to Windsor Castle, climbing the dome of Saint Paul’s, the Harry Potter studio tour, either Lion King or Aladdin on the West End, and the Imperial War Museum (admittedly my kids have a World War I and World War II interest that not all kids may have). We also plan to pop in to the British Museum briefly to see the Egyptian exhibit and the Rosetta Stone and possibly the museum of London. Kids also tend to like Tower of London.

Also I just checked the Harry Potter studio tour website and the next date to visit is in May so unfortunately you are too late for March. :(

Another vote for the Museum of London, especially if you need to get out of the rain. And the Tower of London is magnificent. When I took my children at ages 8 and 11 there was a scavenger hunt of interesting things to watch out for.

I've always wanted to see the Changing of the Queen's Life Guard: https://changing-guard.com/queens-life-guard.html I hear it's not too crowded and I love horses - maybe your niece does too.

And Harry Potter fans should stop by Kings Cross for a photo opp at Platform 9 3/4.

The Natural History Museum and the Science Museum in Kensington are two excellent musuems, both next to one another and free entrance. Kids love the dinosaur exhibits and the animals (including the insects and arachnids) whilst the Science Museum is very hands on and has plenty of interactive exhbiits and shows for all ages. A short walk to Kensington Gardens will have you at the Diana Memorial Playground which I'm sure your niece will enjoy.

Mudchute Farm
Horse Guards by Churchill War Rooms.
Boat Tour on the Thames
Check the Tower Bridge website to see if they might be raising it when you are there?
Madame Tussauds
Watching the Hyde Park pelicans being fed
London Transport Museum
Riding a bus. Sit up top.
Riding the London Underground
Diana memorial playground across from the Queensway tube station in Hyde Park
Looking for the Green Parrots by the Round Pond in front of Kensington Palace
National History Museum
Children’s zoo at Battersea Park

What is your niece interested in? I'd find out her interests and then start there with your planning.

I'm taking my two daughters to London in August; they'll be 10 & 6. My older daughter wants to see Windsor Castle because she watched the royal wedding on TV last year and was enchanted with it. Both of them also said they want to see "the palace where the real Queen lives." The fact that England has a real Queen is interesting to them. My younger one is also really into Egyptian things right now so we'll probably go to the British Museum to see that. Neither of them is into Harry Potter, so even though that's often on lists of what to do with kids in London I'm not going to waste the time/money on it.

I don’t have kids, but all the kids I’ve seen at the Tower of London seem to really enjoy it. There’s quite a lot to see there. I’ve been twice and haven’t seen it all. Perhaps find a YouTube video of it and show her to see if there’s any interest.

"What is your niece interested in? I'd find out her interests and then start there with your planning."

Exactly. For instance, if she's interested in fashion and clothes, the Victoria and Albert Museum has all kinds of period outfits. There may be other things there to interest her - or there may not. Look at the various museum websites to see not only their permanent collections, but also special exhibits. Just note that for the free museums (like the V&A), the special exhibits are often not free, and can be pricey.

If there's a particular kind of food she wants to try, London probably has it. As a bonus, it may take you into a neighborhood you wouldn't otherwise see.

If she hasn't been on subways before (or if she has and she likes subways), she'll probably be very interested in the Tube. Alas, only some stations still seem to have the classic "Mind The Gap" announcements - those are still fun for me, and I'm a long way from age 9. She'll probably like being on the upper level of a double-decker bus as well.

For kids, sometimes it's the most "ordinary" experiences that are the most memorable. In that vein, be sure to have a look at the potato chip selection of any supermarket (they're called "crisps" in the UK - "chips" are what we call French fries). You'll all be surprised by the flavors we wouldn't dream of in the US (like prawn cocktail, or roasted chicken and thyme) and the lack of others we take for granted (like ranch).

This is my trip report from my visit with my 10 and 13 year old boys. We had the best time! Taking my 8 yo daughter next week. Just a fantastic city to visit :)

https://community.ricksteves.com/travel-forum/trip-reports/10-days-in-london-with-tween-boys

Last summer my kids loved: (ages 6, 8, 10 at the time)...

Tower of London - they really liked the Beefeaters tour and the Crown Jewels
Boat ride on the Thames
Playing in St James park/picnic
Walking along the South Bank
M&M store and Lego store in Leicester Square
Hamley's toy store - explored thoroughly all levels!
Hyde Park - Princess Diana memorial fountain (it was a hot day!)
Playing in the Diana playground at Kensington gardens
Riding the tube and also top front seats of double decker buses
Science museum
Natural History museum (dinosaurs and earthquake/volcano exhibits)
Seeing Tower Bridge being raised

We're actually returning for a week over spring break this year we enjoyed it so much! Can't wait - we return in a week and a half! We'll revisit some favorite spots, but also plan some new things: the London Eye, climbing the dome at St Paul's cathedral, a day trip to Hampton Court Palace, visiting Harrod's (never made it last time!)...

@MC, great trip report! I’d love to hear what your daughter enjoyed when you get back, since she’s right in between my daughters’ ages.

Thank you all
I will check everything