I think the story about Tommy Godwin being drafted is probably quite old and Citizenfish tells us that his research indicates that it isn't true. It probably needs to be filed alongside the story that the Dun Run was started by a load of couriers who didn't know when to stop.
Tommy's year record wasn't a record in any meaningful sense. It used the same self-reporting that anybody could send to 'Cycling', and you can do today in the AUK 'Mileater' award.
Everyone would naturally count their club-run mileages, which are paced of course. There was some validation, in Tommy getting proof of passage, and there was a sealed speedometer. But this wasn't a Roads Record Association sanctioned record.
The story told has always been that the 300 plus days were the result of systematic pacing, that the competing manufacturers came to an agreement to stop doing that, and that the mileages returned to what they had been.