Senior officials and military personnel from the Ministry of Defence in London spent a day on Salisbury Plain recently, working alongside staff and volunteers of various environmental groups, helping to clear a 200-metre length of Bronze Age linear ditch.

The work was part of the fifth annual Biodiversity Day, organised by Defence Estates and helped conserve the clearly defined stretch of the 3,500-year-old ditch.

The scheduled ancient monument runs next to the Tidworth golf course towards Bronze Age barrows in the corner of the Tidworth tank driving area.

Protected from intensive military use, the ditch has become progressively overgrown with self-seeding woodland which helped obscure the archaeological features but provided cover for rabbits and other burrowing animals to slowly erode the archaeological features.

Mr Ian Andrews, 2nd Permanent Under Secretary at the MoD, said that the restoration work provided an insight into the way the MoD balances nature conservation and heritage protection, with the delivery of military training.

During his two-day visit, Mr Andrews was joined by representatives from the government's statutory advisers, including Helen Phillips, the recently appointed chief executive of Natural England (formerly English Nature), Vice Admiral Peter Dunt, chief executive of Defence Estates and members of the Defence Estates' committee.

A highlight was a visit to the Iron Age hill fort on Sidbury Hill, near Tidworth, from which 40 hectares of mixed woodland, mostly planted in the 1960s, have been removed in a major collaborative conservation project between the MoD, English Nature, the RSPB and Butterfly Conservation, which attracted EU grants.

Typical plant species are slowly returning to the site, that is also seeing a recovery of the very rare marsh fritillary butterfly.

Mr Andrews said: "I'm delighted that the MoD is making a practical difference to the protection of the environment.

"This day has been a very positive demonstration of both the MoD's and the participants' commitment to biodiversity and the sustainable development of the defence estate."