Now we have Cameron in Davros telling the "colleagues" that "any attempt to force countries into ever-deeper political union is a mistake".
"Britain is a major European player on all of the issues where Europe needs to act - being more competitive, fighting terrorism, combating climate change - we are right out there leading the arguments, making the arguments", he says, "and that is the sort of political action that we need. But a centralised political union? Not for me, not for Britain".
Continuing with the train metaphors, this is rather like him sitting in a carriage on the Brighton train and screaming to the driver not to go to Brighton. In my mind I have the image of Cameron ranting at fellow travellers, "any attempt to force passengers to go to Brighton would be a mistake".
Seeing as the "colleagues" so love train metaphors – warning about being left on the platform, or on the slow train, etc., etc. - we can have another one.
To my recollection from my days on Southern Region (although my memory may be faulty), there used to be a composite train out of London Bridge. It would stop at Haywards Heath, whence it would split. The front portion would go to Brighton and the rear to Eastbourne.
If Mr Cameron really wants a resolution to his Europe problem, there's his answer. He needs to decouple Britain from the EU and allow the "colleagues" to proceed on their way, whence he can take us to a destination of our choice.
The trouble is that Mr Cameron really does want to go to "Brighton". His protests are for show, and he is hoping that people will be taken in. But if he keeps on like this, it won't be Brighton he gets, but the political equivalent of Hither Green.