Quite possibly the worst heavy fighter of WW2, the Belheim 1F was developed from the Blenheim light bomber and saw service as a convot escort, in the battles for Norway and France and later (in the somewahrt improved IVF version) as a night fighter to counter the German Blitz. On its introduction in 1937 the Blenheim was one of the fastest military aircraft in the world but by 1940 it was barely fast enough to catch the latest medium bombers and stood little chance against the German BF 109.
The spherical depression under the model is for mounting it on a 4.5mm BB.