ITP now replaced. With very grateful thanks to the "How to" folks and the general threads with hints and tips.
Bought the DMGRS pump as I didn't see the point in buying all the plastic housing with a, say, Peugeot one and having to strip it all down and then throw away the housing.
https://www.dmgrs.co.uk/collections/...-2-pump-system
For reference the DMGRS pump is VERY quiet.
I double checked with my ear on the end of a screwdriver on top of the unit itself and yes, it was running. But listening at the open fuel flap with the fuel cap off it's quite difficult to hear.
We'll see how reliable it is as I'm not planning to replace it for several years.