Early flowering white rose

I planted a very vigorous white rose two years ago and, frustratingly, have lost the name. It is a thornless climber and flowers very early, in May. It is not repeat flowering. It dores not lose its leaves in winter. I believe it was bred in the 1950s. The flowers are very small, in flat clusters. Can anyone help, please?

Do you have a photo and are you able to post it on here? that is the quickest way 

Could it be rosa banksiae alba plena? It flowers very early and has clusters of small white flowers. Doesn't repeat, vigourous.

I'm sorryRosa Carriola but don't have a worthwhile photograph at the moment and it seems the wrong season to take one. Busy Lizzie, I've looked up rosa banksiae alba plena and the flowers are too large and showy. I believe this is not a species rose and I remember that it had a woman's name (I think ).Thanks for the suggestion though. Actually I rather wish I had bought the rose you suggest. I indentified mine on the net last year and foolishly for a woman of my age failed to write it down, with the inevitable result that I have forgotten it. This year, the website I used seems to have disappeared.The flowers on this rose are not at all showy and you could easily think that it is not a rose. They look a bit like a flattish and not very impressive head of hydrangea or something like that. However, it is a rose. It would help if I could remember which grower bred it but again the elderly brain has let me down.

Look on this site

http://www.classicroses.co.uk/productindex.php?prodfinderformroseColour=whitecream

you may find a picture of it here. Good luck

On the oher hand you may find loads to go on a wish list 

Thank you so much, Rosa Carriola, for taking the trouble to post this information. As it happens,I had looked on this website and a couple of others, but with no success. I found an encyclopaedic site last year with lots of illustrations and got the result I wanted within minutes, but can't even find the site this year. It seems to have been taken down. Rosa banksiae is now on my wishlist, but I don't have room for another big rose, unless I get a brainwave.  

Rosa banksiae has quite small flowers, like a rambling rose, similar size to apple blossom but more double. It is one of the earliest to flower and is almost thornless. There is a yellow one as well. Have you looked under rambling roses? They have smaller flowers than climbers.

Kiftsgate?  Bobbie James?

Full marks for persistence and kindness, but it is neither of them. I think the rose I have is a close relative of rosa banksiae but was bred in the 50s, maybe by Fry's roses. I have lookoed under climbers and ramblers and have tried quite hard. Asking the question here is a last resort since I'm no expert but love learning and am hoping for greater wisdom from a wiser gardener than me.