As you will be aware this is not the ideal location plus I do not know your taste in flowers.

There is a list of possibilities here;

<url>http://www.thegardenersalmanac.co.uk/Data/Plants%20for%20purpose/Plants%20for%20purpose.htm</url>

Hi do you want shrubs or perenials or annuals? or a mix of both?

I have an extremely shaded area in my garden and I always answer these questions with Shasta daisy either highland dream or Leucanthemum x superbum. These plants are amazing in the very dark and gloomy part of my garden they grow quite high I would say to above my knee and they spread with a fantastic display of large daisy like flowers all summer long. I have planted next to these Helenium " Moerheim Beauty which will grow to a similar height and have orange flowers, I thought the orange would brighten it up too. Also I have planted Rhodedendrum and Hydrangeas and Penstemom "Pensham Plum Jerkin". Growing up the fence behind these I have a clematis "Princess Diana which also does really well. If you look under plants for shade there will be other suggestions on GOY too.

go to the bottom of the page and click on s for shade. there will be lots listed. The RHS do similar listings too.
also look in my garden list with the tags beech tree, shed bed/border and you'll see the plants I grow in deep shade.
but good doers are always hardy geraniums, ferns, epimediums, ajuga, pulmonaria, lamium, aconitum and japanese anemones. Then most spring bulbs will grow before leaves from shrubs/trees shade them out.

Thank you everybody for your help. Lots to go on. It is a theraputic area for a charity i work for. So your help will make a lot of people happy, thanks.