Thanks, Beejay. That's a thought. I've a leaflet somewhere from people offering to clean them. I haven't got a head for heights, nor a long enough ladder, so It's not a job I'd want to tackle myself.
Lengths of cast iron guttering are about £30 + VAT and plastic considerably cheaper. I had our leaking cast iron stuff taken down, cleaned, resealed, one section replaced and new bolts fitted for £200.00
SandyRoe do you have a window cleaner? Usually bribe mine about once a month to clear any debris from the gutter with a nice cuppa. All workmen like a cuppa!