The answer is 209,331 km2, 80,823 miles2, but more interesting perhaps is how big, or small, our islands feel. Physical geography matters, but so too do our perceptions of space and distance.

Think how often you, or someone else, says “oh no, that’s too far” or “it takes ages” about a visit to a relative or friend, a weekend away, a new house or job. The mental map we have of Britain and the ease or difficulty of getting around it can be life-changing.

What is that mental map? We’ve found that many of us struggle with basic British geography, and tend to overestimate how long it takes to get between some of our biggest cities, especially by train. In effect, this makes Britain feel bigger than it actually is.

We asked people to tell us the straight line distance between ten pairs of British cities. The average guesses were quite close to reality. For example, people guessed an average 93.2 miles for Newcastle to Edinburgh, compared to the actual figure of 91.4 miles. On average, across all ten pairs of cities, people are 16 miles out or, put another way, they are wrong by 15%.

That’s pretty impressive. While our ‘Perils of Perception’ studies have found that Britons have a pretty warped view of our country – being mistaken on everything from the size of the current Muslim population to voter turnout and crime, even our sex lives – we are much better at geographic distance.

People are even better at guessing the time it takes to travel by car between the same pairs of cities, but less accurate when it comes to train travel. We collected guesses for the duration of the fastest direct train journey between the cities and the average error was 16%.

Such distortions are evident in cartograms which use perceived distances and journey times to relocate the ten cities. For the most part, our cartograms show an enlarged country, particularly in the far north-west. The group with the most experience of train travel are less accurate than the public as a whole and their equivalent road users.
As with parents being less accurate about the cost of bringing up children, is this likely to be a case of emotional innumeracy, of train users recalling their poor experiences and unconsciously fitting their answers to these frames? Possibly. Echoing this, we asked a different question – about the average door-to-door single-trip commute time – a reality rather than a timetable, and the public were again wildly out.

This might suggest that our transport system is better than people think, but other research finds a nationwide recognition that our economy and its infrastructure is unbalanced and tilted towards the south of England. We’ve also found an appetite for faster, more reliable inter-city transport, and a willingness to commute further for the right opportunity.

The potential here is to bring jobs, housing, social opportunities and people closer to each other – in effect, to make Britain smaller and better connected. If successful, this has the potential to change our spatial perceptions – the way we see geography, distance and time – thereby lifting our personal and national horizons.