Thanks Sean, From what I've worked out so far.....
Pinch bolts - 1/4 x 1/2 unc socket bolt
Arm retain - 3/8 x 3/4 unc button bolt
Chainring retain - 5/16 x 1/2 unc button bolt
And to replace stem bolts on a Hutch 5/16 x 1"
Went to a local hardware place yesterday and for 4 stainless bolts for the hutch stem was................£36!