Thanks guys.
So, pressurised, left it, pressurised left it, checked bores, no sign of dampness. Plugs all the same colour.
So pulled it out into the open air, pumped it up to 20psi and got my trusty hand sprayer with a bit of washing up liquid in.
Sprayed everywhere, hoses, joints, manifold!! Header tank, return pipes etc.
Guess what, only the brand new pressure tester pump to cap fitting blowing tiny bubbles!!
Fitted an o ring to make it fit properly and bingo. No pressure loss.
So, were the 2 x small leaks that I found yesterday enough to generate the behaviour that I saw? Boiling coolant, loss and hard top hose??
Maybe.....
So now have got engine hot and tested again, no pressure loss. Put blue dye in bubble fitted to header, no colour change.
Checked oil no sign of water. Checked compression and all good.
Can't think of anything else to check.
Looks like we are good to go again!!
What would others do? I think with an engine that runs so close to boiling, I have learnt that even a pin hole can push it over.
Might just have got away with it (for now).
Car back in use and being closely watched for now.
Thanks for all the input, might help others but 'don't rush in and strip engine apart' is the lesson to all I think!