It would be an interesting addition to the British. It would either use the 7.5cm le.IG 18 Infantry Support Gun’s or the Raketenwerfer 43 Anti-Tank Rocket Launcher’s model and have the same range as an AT gun, or a stationary buildable with also the same range. The damage effect would be the same as the 95mm HE or 105mm HE.
Source: https://en.wikipedia.org/wiki/Blacker_Bombard