Dave, wanting to prove the English can picnic just as well as the Germans, sent along this photo of a young couple (NO wedding ring on her finger) enjoying nature, or what comes naturally, on their Triumph outfit. I would suggest the model is a 1930 CSD sidevalver of 550cc, which would have set the fellow (and I'm assuming it's his machine, as he's not wearing a white dress) back £39.17.6, plus the sidecar... a bargain machine, slow but reliable, and able to haul the chair, the girl, and the gear, much more comfortably than the little BMW single in the previous picnic post. Plus, with a sidecar, you can haul a hand-crank gramophone and a few 78's to increase the romantic mood... never mind that the pot to boil your tea fell of the 'chair' and now looks distinctly secondhand. Given the apples and cheese strewn about, it looks like they've already had a bit of a tussle...and I'm beginning to wonder if these were 'naughty' postcards, rather than factory advert photos.
And a note about the sorry state of Triumph literature; 'how could this be', you might ask, 'there are dozens of books about Triumphs', which is true, but the coverage of anything prior to Edward Turner's input (the 'Tiger' 70/80/90/100 and Speed Twin), is sparse and poorly researched, and the photographic stock is even worse. I've got all the Triumph books, but had to pull out a 'Show' issue of The Motorcycle from 1930 to find our model here. There is a recent history of New Imperial motorcycles which has every model described and photographed from catalogs or contemporary press - now that's helpful. Definitely a publishing opportunity for a Triumph fanatic.