Ok so I thought I was just weak and doing things wrong. I have spent some time over the last couple of weekends trying to remove the pistons from the front callipers to no avail. So this week I took them to the motorcycle shop the the mechanic said “No worries give me 5 minutes!”. So about 2o minutes later he came out with one set of pistons removed and the rest still stubbornly in place.
As I cannot buy replacement callipers new I am currently “soaking” the existing one in WD40 hopefully to free it up. Based on the condition of the front master cylinder and the front brake lines I am not totally surprised, the brake fluid has previously been contaminated.
So I have a new master cylinder and I am going to order some new brake lines.
One step at a time.