The RSPB has emerged as a serious buyer of commercial farmland outbidding farmers for a 295ha (730-acre) Wilts arable and sheep farm, which is believed to have sold for about 2.5m.

Although the bird conservation group already owns Grange Farm, a 180ha (450-acre) arable farm in Cambs that it uses as a demonstration unit, Manor Farm at Newton Tony, near Salisbury, is believed to be the organisation’s largest purchase that will be farmed in-hand.

Kevin Prince of land agent Strutt & Parker, which handled the sale, said there had been lots of competition from local farmers and those from further afield.

“It was sold in the face of competition.”

Dr Mark Avery, conservation director at the RSPB, said: “This is the missing piece of the jigsaw for us and will be the RSPB’s first major chalk grassland nature reserve.”

About 80% of the country’s chalk grassland had already disappeared and birds like the stone-curlew, skylarks and lapwings would benefit, he added.

Spokesman Grahame Madge said the RSPB wasn’t waving an open cheque book for more land but would potentially be interested in the right farm in the right place.

These included areas of endangered habitat as well as farms that could be used as new demonstration units for other farming systems like dairying.

In total, the RSPB’s 180 reserves cover about 130,000ha (320,000 acres) of land and one-third of those were farmed to a certain extent, added Mr Madge.