THE Tory party would force all Government departments to buy British food if it wins the General Election next year.

The promise will form the centrepiece of the shadow environment secretary Nick Herbert's keynote speech to the party conference in Manchester today.

In an unashamed bid to be seen to be supporting the hard-pressed British farmer, it will ensure departments – including Defra and the Treasury – buy food for their canteens and official functions that meet British food standards.

The Conservatives hope that by "leading by example" it will encourage more of the £2 billion spent on food each year by the public sector to be committed to farmers in Britain.

Mr Herbert could not say how much of a financial boost the Tory promise would represent, but insisted it would "not be insignificant".

This summer, the Cabinet Office admitted it had no idea whether Downing Street or Chequers had procured British food over the last 12 months, underlining what critics say is the Labour party's antipathy towards the countryside.

Mr Herbert claims not a single rasher of bacon served to the armed forces is British and that the Treasury buys barely half of its food from Britain.

Last night, Mr Herbert told the Western Morning News: "The Conservative party is really getting behind British farmers. Governments should lead by example. Labour's failure to back local produce is shameful."

European Union competition law prevents governments from buying explicitly British meat, vegetables and drink.

But it would be able to bypass the European legislation by demanding Whitehall departments buy food from farms that adhere to the official Red Tractor scheme – an independent British benchmark demanding high standards on food quality – and that farm assurance standards are written into deals.

The Tories have chosen Zac Goldsmith, the party's parliamentary candidate for Richmond, who has a farm near Tavistock, West Devon, to draw up a blueprint to encourage NHS trusts and councils to adopt the buy British policy.

"We can't dictate to schools and hospitals what they buy, but buying British could make a huge difference," he said.

In effect, all Whitehall food procurement must be from Red Tractor farms unless it increases costs. He admitted it was not a "panacea" for all the ills faced by the sector, but that it is "one of the things Government can do to help".

"We are taking this action because we care about local food and we care about the countryside," said Mr Herbert.

The Tories say while some Government departments source up to 75 per cent of its food from UK farms, only 15 per cent of poultry and 19 per cent of lamb served to UK armed forces is British.

To underline the benefits of buying local, the Tories cite the NHS in Cornwall. In 2006, Cornish produce supplied to patients, visitors and staff at Royal Cornwall Hospitals Trust cut food miles by 67 per cent, according to a report by the Soil Association. In total, 41 per cent of the trust's £975,000 food budget was spent on local food.