Stew, I know it is not Indian but is this fantastic Thai restaurant in Holborn (Theobalds Rd behind Adastral House). It was run by a Thai family and they provided food of all different varieties, including Mega-Hot. I ran a megabucks-project from Adastral House and that restaurant was our preferred noshing venue, despite us being Indian curry lovers.
Failing that, why not try the Indian restaurant (not far)
India Club Restaurant
143 Strand
London, WC2R 1JA
Suoerb original curries and good real Indian beer, in a rustic Indian atmosphere. I believe it is an offshoot of the Indian Embassy. It is also a hotel. Marvellous, but only open lunchtimes to 3pm I think, and then open evenings. Also try Brown's in Old St afterwards for a good finish to the meal :

. Just have a bloody good birthday

CP