First UK Zanussis
Early 70s sounds about right to me. I'd have to do a bit more digging around.
The first model in the UK was the DL22, however, this has the filter on the left and is a different shape.
I think your mystery machine is either a DL4 or a DL6. Neither have any option buttons but have the filter in the correct place. DL4 had a single level pressure switch, cold fill only and a 380??rpm spin. DL6 had a two level pressure switch, hot and cold fill and a 520rpm spin. Instruction manuals for all three models are on Serviceforce.
I hope i've not got any more numbers wrong, I'm getting tired!
Tom.