Matt Jackson, head of conservation and strategy at the Berks, Bucks & Oxon Wildlife Trust (BBOWT), said: “We knew that HS2 Ltd engineers were looking at further land take within the site. Now we are very concerned about the effects on Calvert Jubilee nature reserve and the wildlife that will be affected."

Parliament agreed to allow additional provisions to the HS2 Bill that make a number of changes along the line of the route. One of these changes is to dig ground anchors into the nature reserve to underpin a security wall along the full length of the eastern side.

This means digging deep into the reserve, and raises questions about the effects of encountering landfill. BBOWT is also concerned about possible changes to the hydrology of the site, especially as this risk does not appear to have been considered.

"The proposed HS2 line runs along the eastern side of the nature reserve, which is particularly important for both grassland and scrub habitats for black hairstreak butterflies. It is also part of a circular walk around the reserve,” said Matt Jackson.

Read about HS2, the impacts on wildlife along the route through Buckinghamshire and Oxfordshire, and what BBOWT is doing to protect wildlife.