max-man wrote:
Can anyone please recommend an (online?) supplier of waterproof
housings/boxes for mains electrics, ie to house a main fuse box,
circuit breakers, interconnections, etc? ... 2 feet in height
by 1 foot wide.

http://www.uriarte.net/
Catalogue Empty Enclosures Electricity

http://www.rolec-enclosures.co.uk/

http://rswww.co.uk
Electrical, Automation & Cables Enclosures & Fans
Electrical/Industrial Wall Boxes Polyester and Polycarbonate

Owain