On Monday, 29 March 2021 at 21:40:44 UTC+1, Theo wrote:

What's the pitch of the pins? Are there any markings on the body of the
connector?

5mm pitch, and the pin diameter is 1mm so they're sounding 'standardised' to me?

You could try going on Farnell and filter by pitch and
manufacturer to whittle it down.

If you are keeping it you could always desolder the connector and replace
with a matching plug and socket of the same pitch.

Yes, I thought I could probably even solder wires directly to the pins (heatshrinked) and connect them to some Wagos. There a fair bit of room inside the backing plate once the terminal block holder is removed.

I'll keep looking in the hope I can find them. And that they're 80p for a pack of three.