Machine operator_piston rings

[Snoosh]

In 1923 the occupation of my grandmother, then aged 24, was given as machine operator piston rings.  My grandmother was living at home and I presume was working in a factory close by somewhere in Wandsworth, SW London. Has anyone come across this occupation before? Is it perhaps linked to railway workshops that were not too far away?

Moderator comment: only small portions of certificates may be posted to assist with deciphering handwriting.  Since this certificate was typed, it could not be justified.

[wyndham]

There were two main motive power depots in this area.  Longhedge Works (Stewart's Lane) and Nine Elms.  The former served Victoria and the latter Waterloo.  1923 was the first year of the Southern Railway as prior to this Longhedge belonged to the London, Brighton & South Coast Railway and Nine Elms to the London & South Western Railway.