BR RAILWAY SHERWOOD SUPERLITE BRASS & STEEL SIGNAL LAMP BURNER SUIT ADLAKE 1950

It it is from a signal lamp possibly an Adlake but would suit others. It will slot into a standard 24.5 mm aperture in your reservoir - adjuster shaft approx 35mm to the burner centre, stamped British make & Sherwood Bham to the adjuster knob.