Posted: 25/03/2015 at 13:12
I think you may struggle to meet all the criteria that you are after, no rose that I know will keep it's foliage in winter, you may get a few leaves that stick around but they look rather untidy to be honest. I can't think of any white roses that would take shade (that I have grown) but Madame Legras de St Germain will take a bit of shade. It's white, but doesn't repeat flower, still a wonderful rose while it lasts. Oh and it's thornless (well almost).
Another great rose I grow on an east facing wall is Zephirine Drouhin, again thornless, it repeat flowers and the perfume is fantastic. People say it can have disease problems but I've never found this to be true.
I know you say your garden is north facing but is there any where you could put your roses in full sun....that way you would have a far greater choice (but still no evergreen roses)