So..
Tuesday - dug a 60x60x90 hole in the back garden. bent rebar.
Wednesday - got a concrete mixer, mixed near 3/4 ton of concrete.. rebar in, concrete in, setup the pier former, concrete in that too (vibrating all the way to get rid of bubbles), finally set the four bolts in place. Covered and put a oil rad in there to protect against the 2degC.
Today - looking good, mixer to go back, deremmelled the remaining brake disc (used as a levelling device not on a car!).. next week should see it ready for release from the concrete former.