It souinds more like the quality of the soil which needs looking at first. The hedge may well be robbing the soil of any nutrients, so any other plants will not grow too well.
So, the first thing to do would be to drive a sharp spade down between the soil and the hedge, say about a foot inside. This would sever the roots which are robbing your soil. It should not harm the hedge. Then I would get some organic material into the soil, manure, compost, whatever.
After that you can start thinking of plants.

Well, Spring is quite easy. Use your choice of bulbs, especially those that are natural woodlanders. Also, Cyclamen. Above these plant Dicentra spectabilis (pink or pure white forms). These will flower until early summer. Then how about some summer bedding such as Begonias and scented Nicotianas. For autumn, Asters are hard to beat for flower power, try the New England hybrids but check their height as some are quite tall. For winter, Sarcococcas are great with a fantastic scent...and then the bulbs will come up again! I've chosen things that will take some shade as an east facing border gets shady towards the afternoon.Don't forget to take some pics for us all to see!

Agree wholeheartedly with Owdboggy above - that's essential. Also, have you checked what's under the soil of your raised bed? Sometimes people just shove a spade's depth of soil over concrete, which is why the bed is raised, just to cover it up. Dig down and make sure there is more than a spade's depth of soil all over (try shoving a garden fork into it, all the way down, see if you meet resistance). If there's nothing but soil underneath the bed, then do what Owdboggy says. Bear in mind that if the hedge is privet, that's renowned for stealing all the nutrients and moisture to about 5 feet out from the base of the hedge, so not ideal for planting, though there are things you can try in those conditions.
Once you've done that, one thing to remember about what plants you choose - east facing can be difficult for a lot of plants because they'll get early morning sun, so things like Camellia won't flower well because the sun catches the buds before the frost has gone. You don't say how big this bed is - when you've established that there is soil all the way down, and have followed Owdboggy's advice, perhaps you could let us know the size for more of a clue about exactly what to plant, though Volunteer has already made some suggestions above.

Oh thank you all so much.

The hedge is photinia (?) red robin and has grown very quickly so your comments make perfect sense. The soil is probably very bad quality as it was taken from elsewhere in the garden during a big structural re-landscape. It is pretty deep (prob about 2 1/2 feet) but almost certainly in bad shape.

I shall do as you suggest and try and manure some life into it!

As for size, it's a zig zag shape, 15 foot deep at it's biggest and 4 foot deep at the narrowest.

Thanks again. I feel I may be on the road to getting somewhere...

If it's any comfort, Photinia isn't as greedy as privet!

Everyone around my area seems to have planted Photinia the past couple of years . . .must be the favourite of the moment . . .I like it very much . . appears to grow in most situations.

You're right, Megan, it has popped up everywhere and is very popular - believe it or not, 25 years ago you'd have been hard put to buy one anywhere!

I admit it, I have planted one last Autumn, a rather small specimen at the moment. : o )

well, if it's anything like ours it will go mad very quickly. And as a hedge it looks beautiful at all times of the year. I love it when the sun sets on it in the evening - it gives the garden a gorgous fiery warmth.