I don't think I know that one, might look round there next time I'm in the area!

I think finding low/no-carb options visiting any city abroad is:

1. hard work! and

2. a business opportunity just gagging to happen...

Next time you're over, look up our major supermarkets Sainsbury's, Tesco, M&S Food and Waitrose - they've taken to putting local-store type outlets on many high streets (London being a collection of mini-villages with their own high streets, eg Camden or New Cross, instead of a monolithic city) and you can use their branch locators online, they usually have better options for low-carb stuff you can take away and eat in a park, or by the Thames - better by far than pricey carby sandwiches from places like Pret A Manger & Subway.

I don't dine out much (I'm a good cook, and a bit of a cheapskate!) but if I find anywhere useful I'll post it on the main low-carb forums.