Chris J Dixon wrote:

Any other suggestions?

The BG model WP23L has a deep cover to accommodate wall warts etc ...

https://www.bgelectrical.uk/public/downloads/data-sheets/weatherproof/WP21_WP22_WP23_WP24_13amp_Socket_Outlets.pdf

https://www.sparkswarehouse.com/products/WP23L-weatherproof-13A-1-gang-double-pole-unswitched-socket-large-housing