Links to reviews of more casual dining experiences...
At most of these you're going to struggle to spend more than £25 a head for 2 courses (without booze) and some are a lot less than that. In general they're not smart, but that doesn't mean they wouldn't be suitable for clients. More for a mid week treat or the sort of place you'd go to meet friends.
HIGHLY RECOMMENDED
Anchor and Hope - Original Waterloo Gastropub
Angels and Gypsies - Authentic tapas in Camberwell
Bar Shu - Sizzling Soho Sichuan
Buen Ayre - Argentinian Steaks in Hackney
Byron - Covent Garden hamburger chain
Dehesa - casual Soho tapas
Fernandez and Wells - Soho coffeehouse
Firezza - South London gourmet pizza delivery
Hawksmoor - Shoreditch steakhouse
Polpetto - Venetian tapas in Soho
St John Bread and Wine - Offally good
The Gowlett - East Dulwich pub pizza
Vasco and Piero's Pavilion - classy Soho Italian
Zucca - Amazing Bermondsey Italian
HAPPY RECOMMENDING IF YOU'RE IN THE AREA
Bea's Of Bloomsbury - Divine cupcakery
Blah Blah Blah - Shepherd's Bush Vegetarian
Bodean's - Soho BBQ pit
Buddha Jazz - Camberwell Vietnamese
Busaba Eathai - Communal Thai in Bloomsbury and Soho
Maison Bertaux - coffee and cake in Soho
Moshi Moshi - Brighton sushi
Pho - Farringdon and Soho Vietnamese
Sa Sa Sushi - Angel
Sun and Doves - Camberwell pub
The Bear - Great pub food in Camberwell
The Draft House - Tower Bridge alehouse
The Lansdowne - Primrose Hill Gastropub
Zeitgeist - Traditional German bar food
WASN'T A FAN... LET ME KNOW IF YOU DIFFER
Bincho Yakitori - Japanese skewers in Soho
Le Petit Parisien - French bistro in Camberwell
Black and Blue - so-so Borough steak chain
Dim T - Charlotte Street Dim Sum
Vapiano - Soho chain pizzeria