The infamous Synth A, aka ‘Portabella’, developed by David Cockerell in 1971 for Peter Zinovieff’s Electronic Music Studios, EMS.
The original A version needed a separate keyboard, the DK1 ‘Cricklewood’ ,which was also used to control the VCS3 or ‘Putney’ (the better known table top version of this synthesiser, probably on account of Pink Floyd’s Dark Side of the Moon).
The Radiophonic Museum’s keyboard is a prototype DK0, of which only 2 other are known to exist.
The Synthi A became the Synthi AKS, with slightly revised patch matrix. The KS keyboard sequencer was integrated in the Spartanite case.
It also included a Presto Patch which is a very handy thing.
Much information exists on the web about these wonderful instruments which were more often than not found in laboratories, educational music facilities and experimental electronic music studios, including of course the Radiophonic Workshop.
Suffice to say, the Radiophonic Workshop were not alone in the iconifcation of this diminutive briefcase. EMS themselves were the master of this art.