The European Commission plans to simplify its rules on the ideal shapes and sizes of fruit and vegetables and at least one supermarket has promised to take more "wonky" ones.

However, a veteran Yorkshire grower doubts if the changes will make much difference to farm incomes.

The rules governing the degree of bend expected in a banana or a cucumber, the minimum circumference of a cauliflower and other vegetables, have been demonised as "Euro-lunacy" but they date back to before the Common Market and officials say they do not stop retailers selling anything they want to, subject to proper labelling. However, they have agreed that the red tape needs trimming back.

Sainsburys added its weight to calls for reform this week, claiming it had been forced to abandon a plan to sell odd cauliflowers as "zombie brains" for Halloween.

It said it wanted to be able to sell such products anyway, because they could be 40 per cent cheaper than perfect specimens.

The Liberal Democrats' new shadow minister on Defra affairs, Tim Farron,said: "Over 20 per cent of domestic produce is thrown away because it doesn't meet EU regulations. This is a huge amount of waste."

But Michael Mann, the European Commission's agriculture spokesman, said Sainsburys and Mr Farron were repeating "Euro-myths".

He said: "Cucumbers do not have to be straight. There are grading rules, which were called for by representatives from the industry, to enable buyers in one country to know what quality and quantity they would get when purchasing from another country.

"Nothing is banned under these rules, they simply help to inform traders."

A vote expected to take place on November 12 should repeal EU marketing standards for 26 types of fruit and vegetable. Marketing standards will remain for 10.

Graham Ward, a veteran Yorkshire grower and NFU spokesman, said the foundations of today's rule book were laid in the 1930s.

"One intention was to try to make sure only the best got to market, at times of over-production. Another was to make sure I could call Venezuela and order 10 tons of X at Grade N and know what I was getting. Various bodies have added to the rules over the years and there may be room for simplification, which is what the EC is up to. But it is still important to have grades everybody understands."