He was born in
Dorchester on 24 February 1864, the son of Thomas Thorneycroft, and his wife, Jane Whitelaw. The family moved to the Mansion House in
Tettenhall in his youth. He was educated privately at
Charterhouse School. He studied Mining Engineering at
Owen's College in
Manchester then was apprenticed to
Simpson and Rankine in
Glasgow. He trained as a mining engineer and based himself in central Scotland. His first position was as manager of Merrytown Colliery in Hamilton from 1889, then moving eastwards, and living at 25 Snowdon Place in
Stirling from 1896. In 1894 he rented the Plean estate to open a colliery, from 1897 living himself on-site at
Plean House, near
Stirling in central Scotland, the former mansion of the late William Simpson of the
East India Company. The estate had been historically part of the lands owned by
Robert Haldane of
Airthrey Castle. Plean House was built by Francis Simpson in 1819. The Simpson family held title to the estate until 1922 when it was bought in its entirety by Thorneycroft. Of the 520 total mining workforce 12 were killed at 59 injured. In 1937 he came to relative fame in Europe by experimenting on recreating conditions to create a vitrified fort, this being in liaison with archaeologist
Vere Gordon Childe. These experiments took place at one of his own mines:
Plean Colliery. He retired to Strete Ralegh, a mansion in
Whimple,
Dorset but retained Directorship of his Plean and Lochgelly companies. He died in
Weymouth on 26 April 1954 aged 90. His colliery at Plean was closed in 1963 and is now just marked by a memorial. Plean House was vacated by the Thorneycroft family in 1972 and is now ruinous. The estate and former colliery and slag-heaps were acquired by Stirling District Council in 1988 and the colliery area relandscaped. The combined areas now form Plean Country Park. ==Family==