Hi there. It could be anything. You really need to provide a lot more detail (shrub, perennial, annual, evergreen, deciduous, flower shape, leaf shape, when it flowered, and so on).

How about the Himalayan Blue poppy, Meconopsis betonicifolia? Google it and see.....

Thanks for your comments my neighbour says she thinks it was Anchusa I think she might be right have Googled it and it certainly looks the same.

anchusa certainly fits the description. there is a wild one called alkanet.

Oh yes, very blue flowers, I have Alkanet Sbg, it is a real thug, with a great long tap root. After years of trying to eradicate it, up it pops again!
Just been reading about it and the root is used in dying fabric.....produces shades of purple and purple greys.

Sounds like Alcanet to me too, it does have quite rough leaves and stems, and is also rampant in my garden. But as you say it has the bluest of flowers.