I think the question might be about the fuse value, rather than position. The "35" in the manual is in a different rating system than we commonly use today; and represent the current that will cause the fuse to blow "instantly" rather than the current that it can carry continuously. The difference is about 2:1 ! (And in fact, the original fuses usually had an insert inside that read "17.5 amps continuous".)
So, while it is probably best to buy a reproduction Lucas "35 amp" fuse from the usual suspects (the original fuses were also slightly different dimensions); an AGC 20 makes a good substitute.