Gill Sans Shadow No. 1 (series 406) was released in 1936. [Reichardt 2011] Originally caps only? Ludlow’s Umbra (1935) is very similar. Stephenson Blake offered a wood type version named Shadow Sans. [1936 specimen] Gill Sans Shadow No. 2 (series 408, 1936, undigitized) is slightly bolder. Gill Sans Shadow No. 3 (series 338) is an earlier release (1932), to be combined with the caps from the regular 262 series for chromatic effect.
The name of the digital version is Gill Sans Light Shadowed (w/ lowercase, used for sample).