...
... that by saying Tr. 1 isn’t airworthy,
And why for example Spanish T1s are airworthy and ours aren't
If you want black and white, I can't help you. How many shades of grey would you recognise ? It's 'caballos de carreras para hipódromos' mi amigos.
I don't know how other countries measure their 'airworthiness' but I am given to understand the Spanish Air Force is in the process of upgrading some of their Tranche 1s to include AESA radar. That'll never catch on here. Upgrading is an idea which seems to be out of favour in the UK. "Throw it away - Buy New."
If you keep full records of maintenance, repair, modifications etc. instead of neglecting or actively destroying them while the aircraft is still in service, and ignoring mandated regulations as well, you would stand a better chance of proving and maintaining a safety case. The UK has 'bad form' in that respect.
LFH