Thanks for the comments.

I was told they would only aggressively machine polish a car once, this more so on my Series 1, I guess this given the age of paint!? The trick is taking off just enough to remove swirls and scratches, but not so much you leave the paint vulnerable!
They spent along time mapping the paint depth prior to polishing, & as Selcouth mentioned above, the variations can be very surprising, even more so in cars such as ours! One down side, they pointed out a few imperfections which I had not, & would never have noticed!!!

For me you really notice the difference during & after cleaning the car, its just seems so much easier, & with a very quick polish with a detailing spray, she comes up looking like the day they left.
It is a lot of cash, but well worth it.
PS. Simon – Indirectly you led me to these guys, you may remember posting a while ago about a Talkmorgan photo shoot with Flow Images in Bristol, this never went ahead, but whilst talking with them about it, they recommended JDs services!