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However date can be key to pricing. With some notable exceptions (such as the desirable series of bird and animal carvings) collectors make a distinction between pieces made during the Robert Thompson era (pre-1955) and those made by a subsequent generations of the family firm.

As a general rule, the earlier the piece, the closer it will be to the original design and the better its colour and patination. Dating is achieved by close analysis of the construction details that changed as the century progressed.

Some of these details can be seen in the remarkable Mouseman commission created for the Horlick’s factory in Slough that Sworders of Stansted Mountiftchet are selling on October 9. The viewing opens on October 5.

The Horlick’s factory in Slough

The Horlick’s factory in Slough as it looked in the 1930s when Robert Thompson was commissioned to provide the office furniture.

This cache of approximately 80 lots were made by the Thompson workshop in the 1930s for a new office wing at the factory.

The chairs in this consignment have all the attributes of early models: solid panel backs, a ‘rush rail’ mortised and tenoned to the front legs and upholstery of interwoven leather.

Some pieces, such as a dresser with the letter H and the date 1930 (estimate £6000-8000), have the added bonus of elaborate Arts & Crafts style ironwork, probably supplied by the talented Kirkby Moorside blacksmith Will Dawson.

Others are those specifically mentioned in Thompson's archives. For example a bookcase with a single adjustable shelf and a latticed cupboard listed in a ledger is dated December 12th 1938 as Messers Horlicks Ltd., Slough, Bucks, and described as: ‘One bookcase 3ft 10½in x 5ft 4½in high £13’. The estimate at next week’s sale is £4000-6000.