"Solid". Hard-tire bikes' tyres are kept tensioned by a wire inside the rubber (which is hallow, for lack of a better term), which is either brazed or twisted, then released.

The Kennedy had a much more authentic saddle, originally, but a building a mount for a modern Brooks was easiest solution for long touring (and allowed saddle swapping if I preferred). To an untrained eye (or without very largely detailed photos), it is hard to tell one apart. I suppose it's like first getting into road bikes; they all look the same, sort of, at first; poor example though. See below: