Yip mother instinct is normally right and sure enough. Although I did wonder this morning when he started using that hand a wee bit, but when he said it was still sore I thought an xray to check wouldn't hurt.
As it turns out he does have a good fracture in his lower arm about 1/3 way up from his wrist. As it is a bit further up there is the need for the longer cast around past his elbow. He was a trooper and didn't complain once in at the Urgent Doctors even when they were moving his arm round to plaster it. Need to xray again in 2 weeks to check it's healing well but he will need to keep the cast on for a good 6 weeks - so all going well will be off the week before Christmas!
Couldn't keep him at home, so he headed back to school after lunch and was Mr Popular in his class all afternoon - LOL! Everyone wanted to sit beside him, or walk with him!!!
He is very happy in himself and hasn't complained once - that's my boy :)