Its definitely too early for Pieris yet - that's usually late April or May, and the Bergenia here hasn't flowered yet either. When you bought them, they would have been grown in optimum conditions and may have flowered a bit earlier than they will outside in an ordinary garden.

I'm surprised, Bamboo, that your Bergenia hasn't flowered yet! Mine's been in bloom for weeks. The Pieris may not flower well if planted in too much shade. I have a variegated one that only gets sun late in the afternoon in summer and it has lovely red growth but no flowers. Also, give them a chance to settle in first.

My pieris flowers are nearly over and the red leaves are starting to grow. We are much further West than you, Bamboo, (about as far as you can go actually, in Pembrokeshire) so probably milder. My poor bergenia has been overtaken by shrubbery, but as it wasn't a very good one to start with its no great loss.

But often shrubs will take a year off flowering when newly planted, to concentrate on settling in and growing a good root system, so just be patient - it should flower next year even if it doesn't this year.

The Bergenia I speak of is planted in a shady but exposed north facing place, so that's probably why - mind you I've not been there for a week, it could have flowered then. Certainly the Pieris are not in flower currently, though showing some new leaf growth.

What Bamboo says in her first comment is so true. !

You buy these plants, in full flower and the next year late flowers ..... but - they've settled into their new home and they'll flower when the light levels and temps dictate it - no more no less.
Plants are in 'forced' growing conditions so the Garden Centres can sell the goods in flower.

This is the first time I have used this website and posted a question and so it was really nice to find people have taken the time to help. Thank you!
The pieris was bought last year and has put on lots of growth and is looking healthy so I'm living hopefully for it's sprays of deep pink flowers next year.I do live in Northumberland!
But really I should have made it clear that I was using pieris and bergenia as examples of plants I have had previously that have never flowered in several years. My last garden was clay and this one is well drained and I did use ericaceous compost for the pieris.Perhaps the climate is the culprit. Any further ideas?

The climate might make flowering later but it shouldn't halt it altogether, perhaps they needed more light or sun ?
You could try feeding with something like Miracle Grow this year and see what happens, follow their directions exactly and do an experiment to compare this year to the past ones.