“Where London ends” is one of those topics that can keep Londoners arguing happily with each other for hours. Is Romford in London? (Technically yes, despite being the most Essex place in the universe.) Watford? (Nope, despite being on the tube.) Epsom? (We paid good money to live in leafy Surrey – are you mad?)

Officially the city limits lie at the Greater London boundary, but outside the realm of politics this is a pretty meaningless distinction. In places, that boundary runs down the middle of suburban streets. In others, it’s a good two or three miles out into open countryside.

More importantly though, it’s arguable whether continuous urban build up is really the best measure of a city. Picture an area whose residents work in London, use its transport, and rely on its services. Should its relationship to the city really be defined purely by whether or not you can walk from there to Charing Cross without catching sight of a field?

Barney Stringer is a regeneration expert at Quod, who writes a blog about these sort of issues. A few days back, he wrote a post headlined, “Is London too small?”, which includes this rather lovely map:

What’s clear is that there’s an inner ring of satellite suburbs that are, in economic terms, basically dependent on the metropolis: towns that would, in the US version of the jargon, be referred to as “exurbs”. They include contiguous Surrey suburbs like Epsom, Esher and Weybridge; dormitory towns like Sevenoaks, Beaconsfield and Potters Bar; and the entire set of The Only Way is Essex, most of which is either on the Central Line or will soon be on Crossrail.

Beyond that, the size of the commuter population gradually falls away. The areas with the strongest ties to London are clearly spread out along major transport links. Look:

Stringer asks whether, given these tight economic links, it’s time to look at extending the GLA boundary. He writes:

More than 1.3 million people live in the area marked blue. Every day, many of them decant into London. Their council tax does not contribute towards the services they use there during the working week, nor do they get a vote on how those services should be provided.

Is it time redraw London’s boundaries once again, to embrace these areas that already function as part of the city? Or are there other ways to integrate London’s hinterland, perhaps by giving the Mayor of London greater powers over transport and housing beyond London’s boundaries?

The idea of redrawing London’s boundaries is not as unlikely as it might sound. Twice before – in 1889 and 1965 – the national government has redrawn the city’s boundaries to better reflect its physical limits. In the round of revision that happened in the 1960s, some areas (Epsom, Banstead, Cheshunt, Chigwell) were excluded after kicking up a fuss. Others (Romford, Purley, Barnet) were included despite it. Many districts, if told they were going to be included in a new and larger Greater London, would no doubt kick up a fuss all over again.

But today’s Conservative party, at least, might have a very good incentive to extend the boundary once again all the same. London leans towards Labour but, with a few exceptions, those areas just beyond the outskirts are overwelmingly Tory. A bigger London could boost the party’s chances in its mayoral elections for a generation. With Boris plotting his triumphant return to Westminster, this might start to look like a pretty sweet deal.