I would like to thank "cycle tramp" for his complimentary review of my modified Montague BiFrame, which I used on Sustrans long distance rides back in the good old days of John Grimshaw in charge.
The original bike, which I bought new, was a cheap (£260 then) steel mountain bike that was a travesty of the name "Rudge", but it folded.
It now has pannier racks front and rear (and still folds), mudguards, 50x559 Schwalbe tyres, dynamo lights, drum brakes and North Road bars, which makes it for me a sturdy on/off road tourer that will carry full camping gear and tackle rough Sustrans routes and sandy back roads in Poland, as well as carrying a full load back from the farmers market. It will fold in half, which might be enough to count as "luggage" on a ship or train, but it makes quite a clumsy lump. Naturally, anyone with a bit of imagination could build the basic frame up into the bike that fits their personal ideal. However I mostly use a Brompton or a Fold-It for lighter touring, including camping.