These records contain listings of seatholders & officeholders from a number of different synagogues across London:
The records are searchable by name and synagogue, but the image usually gives more detail, including the address of the seat or officeholder concerned.
There are a number of individuals in this collection that may appear in the records of multiple synagogues, use the addresses on the record image to ensure you have the same person.
Start broadly, and narrow down your results if you have too many, your ancestor may appear in a different synagogue than you might expect for a number of reasons. Choosing a place might cause you to miss relevant documents.