Kid Friendly High Tea London

Here is one (no personal experience, just saw it while looking at tea places):
https://rubenshotel.com/dining-and-drinks/kids-afternoon-tea

If you google child-friendly afternoon tea, you will get lots of hits.

(p.s. I think you want afternoon tea. High tea in the UK is dinner. Some places in the U.S. mistakenly use the term “high tea”)

You may want to consider afternoon tea. High tea is an entirely different thing. We had a lovely afternoon tea at The Orangerie on the grounds of Kensington Palace. It's quite spacious and tables were spread out, and doesn't feel too high risk with a tea loving 4 year old. But, I think if you do some research there are probably child friendly specific afternoon teas in London.

When I was checking out having tea at The Library in the County Hall, I saw this. You might enjoy it if you’re Roald Dahl fans. I read the menu to my fourth graders when we were reading The Witches, and they had a good laugh.

https://www.thetwitsafternoontea.com/

In December we went to the small and casual The English Rose Café & Tea Shop for afternoon tea. It is close to Buckingham Palace.

Another place that has teas for children ages 4-11 is Mad Hatters Afternoon Tea @ Sanderson London. It has a separate children’s menu. We haven’t been to this one.

Here are two afternoon teas specifically geared towards children.

One Aldwych https://www.onealdwych.com/food-drink/charlie-the-chocolate-factory-afternoon-tea
Built in 1905 as the headquarters for the Morning Post newspaper, One Aldwych on the edge of Covent Garden is one of London’s more distinct buildings, which houses Art Nouveau elegance with a little Parisienne flair; namely Charlie & The Chocolate Factory Afternoon Tea. Ideal for children, the interactive dining experience includes fizzy lifting drinks such as the crowd-pleasing water pistol punch that arrives in a glass teapot that looks as though it might explode at any given moment to warm-from-the-oven-scones, chocolate milkshakes, and candy floss. Of course, there is also an excellent selection of tea for the adults and a tasty offering of finger sandwiches and other savouries (with refills promptly offered) but the focus here is on the sweet things in life, which is just as Mr Willy Wonka would like it.

The Classic Afternoon Tea London Sightseeing Bus Tour. https://b-bakery.com/london/bus-tours/afternoon-tea-bus-london
Our exclusive vintage Routemaster buses wind their way through the heart of Central London, offering a unique blend of delightful sightseeing and delectable Brigit's themed afternoon teas on a classic double-decker bus! s you sip your tea, you'll soak in the vibrant culture, iconic landmarks, and rich history of London. Our London Routemaster bus will treat you to breathtaking views of renowned attractions like Big Ben, The Houses of Parliament, Westminster Abbey, St James's Park, Hyde Park, The Royal Albert Hall, Marble Arch, Nelson's Column, Downing Street, and many more. It's not just a tea; it's a journey through London's heritage.

I don't know, Mardee. I'm a pusher when it comes to the tea bus, but for a 4-year-old? If he can tolerate a 90-minute bus ride AND follow instructions to only take a sip when the bus is stopped, then definitely take him. The cups have lids, and there's a cup holder. The food is nice. And they have Peppa Pig and Paddington Bear themed rides. And it's on a bus. Little kids love a bus.

Love this forum, you all are wonderful! Thank you so much for these recommendations, I'm researching now and will definitely choose one of these. Thank you again!

I don't know, Mardee. I'm a pusher when it comes to the tea bus, but for a 4-year-old?

Hey, I’m just the messenger passing info along. :-) .

The Ampersand Hotel in South Kensington has exactly what you want, an afternoon tea designed for families with young kids:

https://ampersandhotel.com/eat-drink/apero/jurassic-afternoon-tea/

Gee, these all look like lots of fun! I wonder if adults can attend any, even without kids in tow?

Are these opportunities to clue in children to NOT stick their pinkie out when holding a cup? And will kids hopefully not get too much of a sugar buzz from the experience?

Chiming in to add the Peter Rabbit tea! Reasonable price for both adults and kids, and looks adorable!
https://artoflondon.co.uk/events/peter-rabbit-afternoon-tea-at-the-dilly-hotel-piccadilly

I know there are more like these. Hannah Ricketts has treated her nieces to tea a few times (the kids are older than 4, but are still young) and you could look up her videos on YouTube. She rates for price, experience, and value for money.