David wrote:

Looking at diamond drill sizes they are 38mm and 52mm, so logically you
use a 52mm core drill for 40mm waste.
Just double checking as it seems like a lot of over size.

Supplementary - recommendation please for source of one off setup to drill
50mm(ish) hole through 300mm brick cavity wall.
Screwfix or Toolstation?

TS do a 44mm masonry holesaw, if you have an existing arbour take it
with you to check whether it fits, or you need to buy an arbour too ...

https://www.toolstation.com/shop/p28954