good to see you back. Julie Limehouse was I believe in contact with Maureen Hanratty at one time, so maybe if you dropped her a PM she could help.
Re: the 'back seat of a bus', my own feeling is that JH told France about this hiding place well before the A6 Murder. I don't suppose bus-cleaners even bothered to report any findings under the back seat, but a gun + ammo was a different matter. If JH is adamant that he didn't dispose of the gun there, then either he was not being truthful (given the dreadful predicament he was in that would be understandable) or someone else planted it. Any suggestions as to who that 'someone' might have been?
We are suffering from a plethora of surmise, conjecture and hypothesis. - Sherlock Holmes, The Adventure Of Silver Blaze