Henry Platt Hall was born at Salford on April 9th 1863, the eldest of four children. His parents were William Hall, a surgeon, and Louisa (nee Platt).
He was educated at Manchester Grammar School, and joined Platt Bros in 1880 at the age of 17 and became a director in 1897 and chairman from 1920-1924. He was the grandson of Henry Platt the founder and the nephew of John Platt MP who was responsible for the firm flourishing in the mid to late 19th century.
King George V and Quuen Mary visited Platt Bros in 1913 and a souvenir edition of the visit was published.
http://www.stanwardine.com/Souvenir_Platt_Bros_Visit.htm Extract from Kellys directory of Lancashire, 1924:
Platt brothers & co limited, engineers, iron founders, machine makers, colliery proprietors, Hartford new works, Featherstall road south; Hartford old works, lower moor; Jubilee colliery shaw; Butterworth hall colliery, Milnrow and Hartford chambers, 2 St Anns place, Manchester.
Henry Platt Hall lived at Toravon, Newport street in Oldham in 1924.
He also lived at Pentre Uchaf before acquiring a Welsh estate at Pentrehylin Hall, Llanymynech. He was High Sheriff of Montgomeryshire in 1928.
In the 1939 register, he was living at Pentrehylin Hall (Occupation: Mechanical engineer). He had a butler - Alfred Barnett born 15 Oct 1874, and two domestic servants - Alice Holloway born 27 Jun 1916, and Catherine Roberts born 16 Aug 1906.
He became an eminent numismatist and after his death his coin collection was sold with the British Museum describing it in its quarterly journal of April 1951 as 'one of the last great collections of Roman coins in this country'.
Probate: HALL Henry Platt of Pentreheylin Hall Llanymynech Montgomeryshire died 15 December 1949 Probate London 5 May to William Reid Hall engineer and The District Bank Limited. Effects £138,777 1s 11d (£4.5 million in 2015).
Coin Sale Catalogues:
http://www.stanwardine.com/h_p_hall_coin_catalogues/index.htm Coins currently at the British Museum:
http://www.britishmuseum.org/research/collection_online/search.aspx?people=66978 
