For a gutter to be priced in at £50.00 IMO it has to be a very basic setup, just a single run of guttering on two sides of the property, nothing else, and that'd be just to clean it out, not clean it off.
IMO gutter jobs need to be good earners, its a dirty, dangerous job, thers no way Id do it for the same rate as windows.
I had one custy want me to do a dangerous gutter clean for him, I explained the dangers of the unsafe ladder angle and position therefore it wasnt safe to do, his response was 'well you're flyers say you clean gutters, so you either clean gutters or you dont' I suggested (and it was honestly meant to be a constructive suggestion) that he could get a ladder and do it himself. Not a happy bunny, wasnt required to do his windows anymore after that. I think his gutters remain dirty 3 years after that conversation.