Although Mallard will not be in steam for the 75th anniversary celebrations at York’s National Railway Museum, a new Hydrovane HVO1 compressor, on special loan from Thorite, will be lurking out of sight in a service pit below the locomotive. It will not only be used to power Mallard’s whistle, but will drive the motor to ring the bell of sister A4 locomotive Dominion of Canada, the pair forming part of a ‘Great Gathering’ of A4s.

Simon Holroyd, the National Railway Museum’s engineering coordinator, says: “Thorite has come up trumps again for us – no suitable compressor was available on their current hire fleet, but they were pleased to allow us to have a brand new compressor for the duration of the celebrations.”