That's a disappointment. One, (and this is only one) of the possible problems could come from pruning. Hydrangeas flower on the previous year's growth, so if you have pruned them recently it may be that you have pruned back this year's flowering stems. Try leaving them unpruned altogether for a whole season and next year you may have flowers. I say this because I have learned from my own mistakes!
And welcome to GoY!

I had a similar problem for 2/3 years then moved them from north facing and last season moved to south facing and what a differance. This year they flowered profusely

Agreed Ojibway its easy to prune at the wrong time and too much, also they need a lot of water, even in a summer like last year mine needed buckets of water to keep the leaves hydrated, I usually feed them in spring with a general fertiliser but a high potash feed ( tomato fertiliser) may also help

A neighbour has a massive tub-growing hydrangea that she was given, in full flower, as a gift. Subsequent years saw a rapid falling off of the number of blooms, and she says she hadn't pruned at all. On my advice she cut it back (far more radically than I had intended), but took EVERY stem back to within a couple of inches of the ground. Two years on it has had the most magnificent display of flowers I have ever seen. It might also have been due to the recommendation that she use an acidophile solution for watering, or a combination of the two, but it worked! we have quite hard water here, so that might have been a factor, too. Here, we get incredibly high summer temperatures, so placing it in light shade instead of full sunshine helped as well. I somehow doubt that will be a problem in the UK, though.

we have out moments Gattina.....its just that we never know when to expect that summer day.....:o))

Usually round about December, isn't it, Pamg? ;o)))))

actually a few days ago was lovely....unseasonably warm.... its bright and sunny now but the wind is really bitter, last year april into may was warmer than the summer!

thats tthe british, always talking about the weather.....:o)