Been going on a year or so now. DS regularly poos his pants, most days in fact unless I tell him to go to the toilet. We went to the Dr and she has suggested Movicol to make him go more often, even though he has never been constipated and a reward chart, rewarding only when he goes without a prompt from me. She was surprised that he has never had constipation or (as far as I know) had a bad experience with the toilet. She felt his tummy and looked for a fissure, no problems there.
DS doesn't seem bothered about this at all, not with me getting cross and the reward chart isn't really inspiring him either. He loves access to our computer but even time on the computer doesn't seem to be enough of a motivator to not poo his pants.
Looking for inspiration really. Dr also suggested a leaflet called 'Sneaky Poo', I've had a quick look and not that impressed with it, not sure it will work. I don't know how to make him bothered by this so that he wants to change!! He seems happy with the status quo.