Ian,
As always your bulb log is very interesting!
I have grown Colchicum montanum outside for several years, and I find it hardy. The site is a raised bed at a Southwest facing wall. Over them is a pear tree at the wall, which shields for the worst rain. I give them no winter protection. I started with a single bulb and have about 20 now, some of them in pots but most at the original site.
I look forward to hearing more about your Sternbergia sicula. I have sicula 'Dodona Gold' two places in the open garden. A clump close to the same wall as above and a clump 50 cm from the wall. The ones at the wall do MUCH better than the others. When they flower I will post pictures of both.
Poul