As the latest beet campaign starts at three British Sugar factories next week growers will be shielded by a new frost insurance policy.

Following the disastrous crop losses two years ago, the National Farmers' Union has negotiated an industry-wide policy to protect all 3,500 growers in the event of a lengthy period of sub-zero temperatures.

It was estimated that total losses were between �11m and �15m, when growers were unable to deliver severely frost-damaged beet in the 2010/2011 campaign.

Growers will be sent policy details next week ahead of the official opening of the world's largest beet sugar refinery at Wissington, near Downham Market; Bury St Edmunds and at Newark, Nottinghamshire.

The cost of the frost insurance will be 12.75p per insured (approved) tonne, which will be invoiced by British Sugar based on the grower's total contracted tonnage for this campaign. This cost has been incorporated in the 2013/2014 beet price. Fenland farmer and NFU sugar board chairman, William Martin, said: 'British growers are used to tackling the challenges that come from harsh weather conditions, but the severe frost two years ago made it quite clear to our farmers and the industry that more must be done to protect them when crop losses are unavoidable.

'We are pleased to have secured the introduction of the frost insurance in response to the calls from beet growers. This policy will provide a financial safety net if we face another difficult winter and damaging frosts, helping provide security for growers against the risks posed by long campaigns.'

The cover provided by the insurer, NFU Mutual, will be limited to a maximum of �15m and a severe 'frost event' is defined as the average minimum temperature of minus 4C or lower for a rolling 10-day period, up to and including January 9. Three Met Office weather stations will be used to establish whether the 'frost' trigger has been hit – Marham, near King's Lynn; Wattisham, near Bury St Edmunds and Waddington, near Lincoln.

If the temperature at any of the stations has reached the trigger, the insurance will apply to the entire contract crop in all beet growing areas.

The NFU, which has negotiated on behalf all growers, said that the policy cover would be activated if the trigger point is reached after October 1 and before December 31 or between January 1 and 9 and at least one day in December which contributes to the rolling 10-day average.

The frost insurance has been designed as a safety net, but it only covers up to 50pc of the value of the beet, which has not been delivered.

Therefore, it remains in the grower's interest to deliver as much as possible. Further, if the yield loss is 15pc or less, there will be no insurance pay-out.

Based on historic weather data, a 'frost event' of this kind has happened in 10 campaigns since 1950.

In the past 62 years, such a claim could have made in 1961, 1962, 1973, 1978, 1981, 1991, 1996, 2009 and 2010 – therefore, a probability of 16.13pc, or about a one-in-six year event.

n Cantley factory, which celebrates its centenary, will start operations on Tuesday, September 25. Grower Bill Alston, who then farmed at Hardley Hall, near Loddon, recalled delivering beet to Cantley until 1957 in the Wherry Albion. When he started the mid-1950s, it cost 2/6d ton to ship and went up to 3/6d (17.5p) ton for the 1955/56 campaign.

He recalled too that for farm staff it was quite a job pushing a wheelbarrow, loaded with 5cwt (254kg) of beet across a narrow plank, to tip into the hold.