True seed Bedfordshire Champion Onions

Where can I buy original Bedfordshire Champion onion seed from? Last year I grew four 25ft rows of this onion,from four different seed merchants each row looked different in colour Leave shape was different and one row had flat onions instead of globe, I have been growing this onion for over 50 years with out any trouble now this year 80% of my stored onions rotted This never happens to original Bedfordshire Champion onions  Can any one help please. Bob Palmer.