I have enjoyed "Purple Top Milan" turnips for several years. This year,
they grow and look normal but lack flavour and are rather bitter.
Another variety, "Oasis" grown alongside this year is fine.

Seed for the "good" Purple Top Milan came from Suttons. The "bad" was
Homebase own label.

Is it possible that different suppliers have different strains of a
variety with very different quality?

Steve Harris - Cheltenham - Real address steve AT netservs DOT com
A useful bit of gardening software at http://www.netservs.com/garden/