Wiska Combi 607/5 40A Grey IP66 Weatherproof Junction Adaptable Box Enclosure With 5 Way Connector   £10.79

Until you handle one, you can't appreciate how good these are- even the manufacturer doesn't list all the great features! Like:- quarter-turn captive lid fasteners; two-shot moulding includes all side cable entries, lid gasket, and three rear entry options; lock wire tabs for the lid; 2 threaded reducing adapters; removable, relocatable 5-way terminal strip; multiple mounting bosses in the base; mounting points in all four corners, outside the sealed area. There's probably more, that I haven't spotted yet! The plastic feels great- tough, not brittle, not soft- and the grey is pale and attractive with a good texture. Oh- the mounting screw size and spacing is moulded on the back too!
All in all, the best JB I've ever come across- at a great price, and delivered remarkably expeditiously to the USA.