George Griffiths would have been very familiar with this at Ronaldsway in 1937 - an Aldis signalling lamp, with which you can still control aircraft and vehicles - even in 2010. Note that the relevant signals are taped to the side!
At one time this lamp was suspended from the ceiling for easy access, but is little used nowadays,
 2000s ATC Pages
An Island Images picture © Jon Wornham