This is in Northern Virginia. I've cropped and picture and hope this helps. A nursery nearby ID it as Pieris Japonica, but I disagree. I want to say this is a type of viburnum or lilac, but I'm not sure.

Yes: Prunus mume. Might be 'Peggy Clarke'. You can tell Japanese apricot right off by the buoyant carnation fragrance it produces.

Yes we are in Kent, UK. I have googled the name and your are absolutely right. Thank you so much! It makes me realise how little I know, but I still enjoy trying in my garden. You have solved a real mystery and I really appreciate your help and I have to say what a wonderful skill you have. Thank you :-)

i see why they are there .. being invasive.. i would get rid of them ... but i would make it a multi year project ... starting at one end [or both ends] .. and planting something different ... while leaving the rest... to maintain some semblance of a screen ... and then.. each year.. removing another ... or just do it all at once.. and be done with it ... ken