You could try here External Link/Members Only they seem to have good reviews.
Ignore this recommendation!!
This is obviously a bait n switch site to any OrientalChaser such as myself
The Oriental London punting scene is currently pretty dire, however reputable agencies worthy of your time are:
007escorts
Invasianescorts
Olina escorts
NOT the bait n switch site alluded to earlier
You will definitely not be seeing any of the girls in the pictures, unless you buy a flight to Japan and gatecrash a gravure model shoot
For a well reviewed on here, although expensive independent girl, check out ApplePie on adultwork