Posted: 25/02/2014 at 08:25
Louise - for roses for your colonnade this site
has a fantastic search facility down the left of the page - put in the height and other characteristics you want and you'll get great suggestions. There are quite a few climbing roses that'll be very happy in a bit of shade.
Peter Beale's roses are superb. Sadly he died last year but it's a family company and it continues