thanks Globaliser, I hadn't thought about expertflyer...the effective start and end date sounds exactly what I was looking for...
...unfortunately, I think its the route I'm trying to look at which is the problem!
I have hopefully attached 2 screenshots (no idea how to paste the values without splaying them all over the page)...the first attachment is a small section of the BA results...useful information - if I didn't specifically only want LHR.
Code:

The 2nd attachment is from expertflyer, almost perfect with the start and end dates, but confusing me with all the codeshares...
Code:

I guess I will get back to copying and pasting into a spreadsheet.
thanks again...John