New Brocock seals fitted and working as intended, thank you Brocock
BF 1/8 BSP came and does fit the recess, but keeping that as a spare for one day
Also had a fiddle with the trigger and got it totally perfect, almost as good as my Steyr LP10 pistol
To get it this good the spring coils had to be heated with a pencil torch and flattened then trimmed off. Just kept doing a little at a time until the springs were just right. It's an absolute joy to shoot now and brings a smile every time the trigger is pulled