Should it be open at hot idle ?

Had the P38 idle on the drive for 1 hour. Temp coming out of the head was 85 deg c , but the thermostat was still closed. Should it be open at this temp or at hot idle.
Took it for a spin ok on centre. Then put it into sport mode and opened her up to 5000 rpm.
The gauge then wacks up to red. Opened the bonnet. the top hose was bulging and the rad was cold to the touch at the bottom but the pipes the other side of the thermostat hot.

when you bleed it, did you have your heating on? could still be air locked. take the pipe off that goes from rad to to tank little thin one, leave you cap off and the pipe till water comes out of it..

Yes ad the heating on for the initial bleed. Filled the rad and the engine from the top pipe . Will check the bleed tube again, but its odd that the thrmostats not opening.
The top of the rad was 60 deg c and he bottom 33, which wasnt far off ambient temp yesterday. I presume theres no diffence in the thermostat on the thor to the gems engine ?