Sorry to disagree! Hubs like my Le Tour were made for fixed one side and 5-speed block t'other. The hub on that Viking is similar, with a fixed sprocket and lock ring currently unused. I don't recognise the hub with its oil point clip, but it looks well enough made. The rear derailleur is probably a
Huret Svelto, cheap 'n' cheerful but sturdy, p. 56 of Aids. I think that was the one on my bike that was nicked (I hope the thief fell off when they tried to ride it away on fixed!). Still at £16.90 - could be a bargain for someone.
Some flip-flop hubs were available, and still are, for fixed / single speed. If you have a look at pp. 66 & 67 of the Aids booklet, you'll see hubs listed as G/F (gear block/fixed), D/F (double fixed) and S/S/G (single speed/gear block, rather than single sided gear, maybe, but probably just gear?).
The rather lovely road Campag hubs on the previous pages were single sided gear only, but only posh folk could afford them!