Clematis one blooming, one not

I bought 2 Clematis (The President) plants last year, only small last year. I cut back in early spring this year, since then one has grown and bloomed well, the other has grown but no flowers as yet. They are about 5 foot apart from each other so get the same amount of sun. I did change the pot for the non bloomer in early spring, could that have disturbed it? The only other difference is that the one that is flowing is sat behind the outdoor furniture so the roots are always in the shade. Or could this just be a weaker plant? Any ideas to promote flowering? I do feed with a multi purpose plant food. TIA. Also I'm in North Yorks, UK

 

Rule of thumb:
The first year of plant development doesn't count.

I planted a lot of different trees and bushes. Some exploded after planting, others did a while year of nothing. This even varies between plants with the same type, shop and conditions.
If they don't grow in the second year after planting you can start to worry, but it seems like your clematis is getting bigger and stronger every day. So be patient and wait for it.

Edit: maybe someone switched signs on the plants. The one that's not flowering Looks a lot bigger than the other. So it could be a different type that got mixed up. Anyways both look happy and healthy.