Having eaten a number of times at London's only Hyderabadi restaurant (named quite originally Hyderabadi Spice) I was very excited to spot the new "sign" for Deccan Kabab. I went in to see if it was indeed a Hyderabadi place and it turns out it is with a full crew of native Hyderabadis. They've got the full range of regional specialites: haleem, biriyanis, mirch ka salaa, etc. I didn't get to try anything yet as I just had a huge meal at Taqueria Coatzingo, but I'm going to probably go back tomorrow.
P.S. Correct me if I'm wrong on the first bit, but I don't think I am. Also, it's in the location that used to be occupied by the perpetually empty Nepalese/Tibetan place next to the barber shop on the same street crossing 74th St as the rather posh looking Delhi or Deshi Heights place.