I came across this nice old Tilley recently. The font was originally plated, but threadbare so I painted it. I know Tilley moved production to Dunmurry in NI., in 1960/61. The pump and control cock are of brass construction. The pump looks standard type from X246 and table lamps, of the 1950's, the control cock has a design seen on earlier Tilley table lamps, but with a modern plastic knob. I theorise that this was a transition lantern whether it was assembled in Northern Ireland or England I cannot say. Is it possible that the components were made by Willis & Bates, who were contractors to Tilley in the early days, they would have the knowledge and designs to work from, its just a thought' The marking are 961XA, Made in England.
The stamp give a manufacturing date of September 1961. As to the fact that it's got a modern plastic knob, that could easily be a replacement.