According to Philip Ahier, the property was in existence by 1588 and was in the possesion of the Brook Family for "nearly two hundred and fifty years".
Extract from Discovering Old Huddersfield (1993-2002) by Gordon & Enid Minter:
Just past the car park mentioned above, and on the opposite side of the road, modern houses on the left hand side of Leonard Street stand on the site of another of the area's old farmsteads, Flashhouse, which was demolished some forty years ago. The prefix 'flash', which the English Dialect Dictionary defines as a shallow pool, or swamp, suggests that the house, like Black Dyke, was built at a time when the surrounding land was marshy.
Readers will not by now be surprised to learn that Flashhouse, which dates back at least to the sixteenth century, was for hundreds of years tenanted by a family called Brook. The house is not mentioned by name in the Hearth Tax Returns of 1664 but a Thomas Brook of Greene is recorded as paying tax on one hearth and it is quite possible that he resided at Flashhouse which, of course, stood on Fartown Green.
The Huddersfield Rental of 1797 describes the property, then in the tenancy of 'Mr. John Brook', as a house and barn with fold and garden. The appellation 'Mr.' — unusual in the Rental — indicates that he was considered to be of higher status than most of the other tenant farmers of the time. He farmed a number of closes comprising some thirty acres of land lying between Fartown Green Road and the Ramsden Canal to the south east. John Brook, a staunch non-conformist, was a founder member of Highfield Congregational Church in Huddersfield. He was the last Brook to live at Flashhouse and after his death in 1820 the property was let to a succession of tenants including, in 1913, the butchering department of the Huddersfield Industrial Cooperative Society.The main line railway to Huddersfield, completed in 1847, passed within a quarter of a mile of Flashhouse shattering forever the slumbering peace of centuries in John Brook's former fields. Some fifty years later the Midland Railway Company's branch line was constructed only a few yards away from the house itself. The track of this railway which ran to Newtown in Huddersfield has long since been lifted but the broad swathe of land it occupied remains and may be seen, along with two original bridges, by walking along Leonard Street and turning left just before the first modern house on the left.