Have to say I have not yet heard of £60 per hour by anyone I know. £45 - 50 an hour for a full FI and normally £10 an hour less for a new FI(R) or AFI as they were.
Most clubs will tell you this is because they need to have a full FI to cover you sat around the field while you train. True but also a way to make an extra tenner an hour for the company.
Yes fixed wing instructor will get more flying in and it does cost us more to get going in the first place but I have to agree with whirlybird, FI(A)s should get a bit more than some of them I know are being paid.