It’s a movie theater in a bus! These “mobile cinemas” were commissioned by the UK’s Ministry of Technology in the late 1960’s. Inside each of these buses was a narrow movie theater:
Of the seven originally produced, this appears to be the last one standing. It’s been nicely restored to modern day standards (with vintage 1930’s seats) with a Blu-ray player, full Dolby 7.1 surround sound including a subwoofer and an LCD projector.
The bus is doing the rounds at various festivals and fairs in the UK but you can hire it for your private event at their website.