On the basis of my granparents I'm:
3/4 English (2/4 Kent, 1/4 Staffordshire)
1/4 Welsh
Working back to the next generation, though, that equates to:
7/8 English (4/8 Kent, 2/8 Staffordshire, 1/8 London)
1/8 Welsh
And then further back another generation:
13/16 English (8/16 Kent, 4/16 Staffordshire, 1/16 Cambridgeshire)
3/16 Welsh (1/16 Glamorganshire, 2/16 Monmouthshire)
The Monmouthshire falls back to 2/32 in the next generation, and one side were from Dorset originally. All in all, it means I'm mostly English with about an eighth Welsh.