I had a similar problem and was advised by an expert in our local GC to cut it hard back in autumn (about now) feed it with such as fish, blood and bonemeal, worked into the soil around the plant. (I also put in some chicken pellets for good measure!) The first year after you will just get lots of new growth but the year after you should be rewarded with beautiful, big blooms. It certainly worked for me.

Last year was very wet this year it was very dry. Hydrangea means water lover...so you can guess why it flowered well last year and rubbish this. A feed would not go amiss though I would not hard prune unless you want to wait a few years for flowers. Next year water the Hydrangea and it will reward you.

Sorry to contradict you Kildermone, but it won't take a few years to flower but only 2, the first to put on new growth and as Hydrangea flowers on the previous years growth, you will be rewarded with flowers in the 2nd year. You are correct about the water, but I was assuming that as they had flowers up to last year, that wasn't the problem.

" it won't take a few years to flower but only 2"

A few of anything does normally mean 2 :)

I stand corrected.