Overheating again

Hi all,after getting the previous overheating issue sorted a few months ago on the 160,it’s happened again.
I stupidly on reflection left the car ticking over today for about 2 hours to charge battery.Went out to look at it,coolant on the ground,steam,and temp gauge up to the limit.Switched it off,let it cool,topped up coolant and restarted.Tank was rising up to the top after a while and temp gauge on the rise.
There was still coolant in the tank before I topped it up,no mayo,no oil in coolant.But really worried I’ve wrecked the car,any ideas.The head was done 20k ago.
Thanks

could be several reasons, for me it was a clogged toggle valve in the inlet manifold some time ago.

Looking at the photo I would guess that your leak is either the header tank cap or the actual header tank.

When was the cap last changed?

It was changed about 6 months ago at the last overheating incident.
Do you think I’ve wrecked the engine or boiled it,and can you do a second head gasket change,my mechanic reckons it’s a new head,you can’t skim it twice.
Many thanks