Thanks all for your replies - one thing I do love about this forum - no-one holds back in their views LOL!!!!!
I do understand that if I "get rid" of the blue it will come back quite quickly - however once a year I do like to give the old girl a damn good top to bottom clean, if nothing else just to check over every last little bit of her and in doing so, like to get everything back (as much as possible) to when she was first new. The rest of the time she gets ridden with a reasonable wipe over to keep her tidy. Given we are in lockdown at the moment, now seemed to be a good time to do it, and the headers were the last bit to do.
Like you @B15ape1981, I do actually like the bluing on the pipes, but also like to cut it back so it can re-asset itself in the coming year.
Thanks for all you comments, also thanks for the recommendation @fizzer, hadn't seen that stuff before