Any thoughts on how to achieve a leak proof shower (sans silicone)? I'm not keen on the moulded fibreglass pod look such as Coram or Douglas James. How about stainless steel? Could the sides be welded to a base on site (to avoid access difficulties)??

I recall seeing a magazine article about a French architect who had a shower above his roll-top bath. The walls were lined with zinc and the water drained into a gutter just below the rim of the bath. Not the same as my situation, which involves a shower cubicle, but I liked his outside-the-box thinking.

Silicon doesn't go mouldy if you spray regularly it with a dilute solution of Tesco's 15p/L bleach.

http://www.tesco.com/groceries/product/details/?id=260550096

Interesting ideas from owlman. You could also install an oversize tray with the glass enclosure/screen inside the tray so water drips into it rather than sealed to the top of the tray.

I do like the idea of an oversized tray with glass enclosure inside. A bit like the old-fashioned freestanding round ones that match roll-top baths, that have a curtain all the way round. You can see where the water is going (though curtains not such a good idea with a kid around). Space will probably prohibit that though. Not so keen on upstands with tiles/panels as that would still require silicone, and there's always the risk of water creeping up through capillary action (no?). Same for wet room type installations - it seems to me there is always the risk of leaks if the structure moves a little. I'm liking a stainless steel solution as the joints can theoretically be made 100% waterproof.