Suggestions for kid-friendly food while travelling in London?

I will be in London with my American niece and nephew (12 and 14) and want casual food, not from a chain like KFC, TGIF, or McDonalds, but my experience eating in London is all very high end, Indian, or Chinese. I don't think bangers and mash or guiness and steak pie in a pub will work. They are good kids, travel alot and are not picky.
...not "too" picky, I should say - they are kids, after all
we'll be doing alot of Harry Potter touring... Australia House, Kings Cross Station, etc., if that helps
Specific places, PLEASE! I know London well, just not these types of places... and NOTHING TOURISTY, please, like Rainforest Cafe.

There are crap loads of sandwhich places in London that you can just go in get a sand which and sit down and enjoy yourself, especially in the more touristy areas.

Most of the restaurants in like the Theatre district along the Strand are pretty low end casual and great! You just got to wonder along the little alley ways and there are thousand of nice little places ... The closer you get towards Charing Cross and Trafalgar Square the higher end the restaurants get, not to mention Oxford Circus and places like that are going to be twice as expensive just just walk a little aways from them and you'll find a nice quiet little restaurant

There really are thousand of places to choose from so I can't be very specific but I always liked going to the theatre district for dinner. I really enjoy the atmosphere ther and all the unique little shops and weird people... But hey I love weird people!

Seriously when you are in the "tourist" areas the food and drinks will be 2-4x as much ... So like I said wander away from them a bit otherwise you'll get screwed ...

McDonalds are quite good. They have a new Healthy range and plenty of Fruit

If you want a sit-down meal, there are a few kid-friendly restaurants, Giraffe is very good (google it, it should come up, they have a couple in London now) and there's also a Rainforest Cafe in Central London somewhere as well.

http://www.london-eating.co.uk/occasions/kids.asp


1. giraffe restaurant (sounds like a fun place!)
http://golondon.about.com/od/guidereview1/gr/giraffereview.htm

2. morelli's (sounds delicious)
http://golondon.about.com/gi/dynamic/offsite.htm?zi=1/XJ/Ya&sdn=golondon&cdn=travel&tm=2&f=00&tt=14&bt=1&bt s=1&zu=http%3A//www.morellisgelato.com/

3. leon (family friendly, healthy food)
http://golondon.about.com/od/guidereview1/gr/leonreview.htm

4. rainforest cafe!
http://www.toptable.co.uk/venues/restaurants/?id=1792&refid=ggl05&gclid=CLPM-IL43ZICFRpOagodHEFP-A