The National Trust's first nature reserve is marking its 120th anniversary this year.

The trust claims that the wetland reserve at Wicken Fen in Cambridgeshire is the most species-rich area of the UK with more than 9,300 recorded, including 25 that were new to the UK and seven declared as new to science.

The most recent discovery, in March, was a flat bark beetle in a pile of cut sedge near Wicken Fen’s mill.

The silvanus recticollis, which is around the third of the length of a grain of rice, had not been found in Britain before.

The newly-discovered flat bark beetle. Credit: Allan Drewitt/National Trust

Stuart Warrington, the trust’s wildlife adviser for the East of England, summed up the reserve’s philosophy by quoting the 1989 Kevin Costner film Field Of Dreams, in which a corn farmer builds a baseball diamond in his fields.

“If you build it, they will come,” said Mr Warrington, referencing the trust’s ambition to create an ideal environment for many species.

As part of this, free-roaming highland cows and konik ponies were introduced in 2001 to spread seeds which they carry in their hooves, mane and coat.

A Highland cow rests beside a mere at the National Trust’s Wicken Fen Nature Reserve. Credit: Joe Giddens/PA

Countryside manager Martin Lester said fenland once dominated East Anglia but now accounts for less than 1% of the landscape after much was bought by wealthy investors and drained for farming in the 17th century.

He said villagers who lived off the land, known as Fen Tigers, resisted and vandalised drainage pumps.

The fen survived and later became a draw for Victorian entomologists with their butterfly nets and Cambridge University researchers alike.

Konik ponies spread seeds which they carry in their hooves, mane and coat. Credit: Joe Giddens/PA

It faced destruction once again during the Second World War with plans to use it as a bombing range, but was spared when it was found that a plant found there could be used to make time fuses, Mr Lester said.

Alder buckthorn, when burned, produces charcoal with a very even burn rate.

A rare great crested newt rests on a tree stump at Wicken Fen. Credit: Stuart Warrington/National Trust

Wicken Fen, a two-acre piece of land when bought by the National Trust in 1899, now covers almost 2,000 acres and the trust wants to extend it further to 13,000 acres.

Several species including cranes, Norfolk hawkers and otters, have returned to the landscape after an absence of several decades, and the reserve is home to 188 endangered species, including the cuckoo, great crested newt and soprano pipistrelle bat.

More than 26.6m people visited National Trust sites last year.

The Trust is custodian of 780 miles of coastline, over 248,000 hectares of land, more than 500 historic houses, castles, ancient monuments, gardens, parks and nature reserves (including 9 lighthouses, 56 villages, 39 pubs and a gold mine).