HS2 Ltd chairman Sir Jon Thompson told a rail industry conference the bat protection structure in Buckinghamshire was needed to appease Natural England, as bats are legally protected in the UK.

The 1km (0.6 mile) curved barrier will cover the tracks alongside Sheephouse Wood near Calvert to prevent bats from being disturbed by high-speed trains.

Sir Jon said there was “no evidence that high-speed trains interfere with bats”.

“We call it a shed,” he said. “This shed, you’re not going to believe this, cost more than £100m to protect the bats in this wood.”

Natural England said it had not required HS2 to “adopt this structure”, but its role had been to “comment on whether the proposed mitigations will work”.

All bats are legally protected in the UK regardless of their conservation status. Located nine miles north-west of Aylesbury, the Sheephouse Wood Bat Protection Structure is a 10m high tunnel-style building designed to protect a colony of Bechstein’s bats, reddish-brown creatures about the size of a matchbox and with a 12in wingspan.