Solved A pretty cream-coloured autumn daisy-like flower? - solved!

This plant grows quite vigorously, and has spread to cover an area of about 10’ by 4’ in the last 15 years of “freedom”. About 2-3’ high, and starts to flower in September until the first hard frost…
(Japanese anenome and choysia leaves for scale)

 

I wonder if it's a Coreopsis ? It reminds me of that ... There's one called 'Moonbeam' with white flowers.
But I'm probably wrong

 

I think you are right, Coreopsis Verticillata Moonbeam

Coreopsis verticillata 'Moonbeam' - tickseed

 

That looks about right. The flowering period and growth description are both underestimates though! I wonder if I can lift clumps when it has gone dormant, to reduce its expanse in its current location, and introduce a little late colour elsewhere. Nowt to lose by trying?