Just wanted to add a quick update and ask another question too (of course).

I contacted my travel insurance and received a quick response of - "if it was mechanical issues then it is the airline's responsibility" - "if it had been weather issues, then we would be right there" - or words to that effect

ORC is being dealt with by GGL line and they have been great and all the missing BA legs have been added and we are just waiting for AA's response now for the legs that weren't flown.

I never received a response to my reply to BA CR - so I called them (via GGL line) a few days ago - spoke to a lovely lady who told me that someone would get back to me via mail or phone within a day.
No reply for 3 days, so I called again, spoke to a less nice person, who basically said that they wouldn't normally be talking to me at all and it was only because I came through on the GGL line. He told me that the last lady I spoke to was away and to wait.

To be honest, I had expected better from CR especially on the out-of-pocket expenses in the UK due to BA losing my luggage as, from my understanding, they are the responsible carrier.

I still also feel that my ticket was with BA and I paid them for it, so they should be handling it in some way rather than emailing me with "speak to AA, not our problem (politely though)" and then not replying.

Is there anywhere to escalate to above CR?

As mentioned, not a huge issue and was very lucky to get out of the storm relatively unscathed, but am a little disappointed.