As far as I know they are still at West Drayton (see
FAA London )
but they do NOT have a airman certification section (if that is what you wanted)
The nearest office for pilot issues is the New York International Field Office.
Telephone: (1) 718-553-0986
Facsimile: (1) 718-553-1360
Federal Aviation Administration
New York IFO, EA29
Halmar Building #75, Room 238
JFK International Airport
Jamaica, New York 11430