Sorry but both your azaleas look as dead as the doornail to me. Did you keep them well watered last summer and are they planted in ericaceous compost in part shade?

I'd scratch the bark to see if there is any green underneath

The green shoots you can see are unrelated to the azalea - they're tree seedlings.
The plants look completely dead to me too - I also note that, in the first picture, the rootball appears to be standing slightly proud of the surrounding compost, which is never a good idea, should be planted at the same level as in the pot they came in. Azaleas do not like to dry out, and if they do, can die quite quickly. Even so, they should never be planted in pots without a drainage hole in the base - I don't know whether yours have drainage or not. It's also possible to lose them in pots if the compost freezes in winter for longer than 2 or 3 days. To check whether they're really dead or not, scrape back the surface of the bark near the centre of the plants - if its brown and dry underneath, they're goners, if there's any green or moistness, they might grow again.

The little green shoots look like sycamore seedlings. If they are appearing in your pots you'll probably find them all over the garden in the next few weeks as well, so keep a look out. The are very easy to pull out at this stage. Sorry about your azaleas.

Plants need to get air in to the roots as well as water and I notice these pots are standing directly on slabs they need to be lifted up off the base with bricks.

Thank you for all your kind comments.

They were indeed planted in ericaceous soil and stones were placed at the bottom of the pots for drainage, so I'm not sure what went wrong :o(

The good news is that there is some green visible when i checked the stems so I remain hopeful that they may be revived. I've pruned them right down, topped up the pots with fresh soil and added some food.
I'll get the bricks underneath the pots tonight.

Does anyone have any suggestions on how often I should water them?

Thanks and Regards
Hopeful Amateur

As soon as the surface of the compost is slightly dry to the touch, but before its shrunk away from the sides of the pot. When you do water, water thoroughly, hard to say how much to give because I don't know how big the pots are - if they're small to medium and in sun, they'll need watering much more often than in large pots in shade.