Thermostatic shower valve with unusually large connector

Hi

I bought a new Hans Ggrohe Ecostat 1001 shower valve to replace the ageing (>15 years old) HG shower valve which is faulty / only cold water.

I thought it was an easy job for my plumber, but when he removed my current shower valve. he said the connector was an unusual size (approx 1 1/4 inch instead of the 3/4 inch) hence the new valve wouldn't fit on.

My plumber said he's never seen such a large connector before, so he's taken away my old shower valve to find out if he could source an adaptor from his local supplier.

Pictures attached below:



Question to plumbers / those with shower valve knowledge:
Are you aware of any adaptor to reduce the connector size from 1 1/4 to 3/4 inch?

(Alternative is to rip out the tiles and redo the pipes/connectors which I wish to avoid)

I've measured it at the widest point and it's 1 3/8 inch (see below)