A front garden isn't usually much good for exercise, so let's focus instead on the number of back gardens. The survey tells us that 85% of back gardens are mostly soft landscaping (e.g. lawn, flower/vegetable beds) and 15% mostly hard (so perhaps not great for exercise). But even an all-paved back garden is better than no back garden at all... so how many of us suffer that?
The 2008 survey tells us that 78% of homes had private gardens front and back, and another 5% had only a private back garden. In total that means 83% of English homes had a back garden of some kind. It's probably a little lower than that today, but let's say 4 out of 5 English households have a private back garden and only 1 in 5 do not.
To dig deeper, the 2008 survey also divides English housing stock into 29% terraced houses, 26% semi-detached, 17% detached, 9% bungalows and 19% flats.
Looking at the graph, a whopping 99% of semi-detached and detached houses have private back gardens, as do 97% of bungalows and 96% of terraced houses. If you live in any kind of house, you very probably have a back garden.
But if you live in a flat, not so. Only 18% of those living in purpose-built low-rise flats have a private back garden, plummeting to just 2% for those in purpose-built high-rise flats. Converted flats do a little better at 33%, but that still means two out of three are gardenless. Combining these categories suggests that only 20% of flats have a private back garden, which means 4 out of 5 flat-dwellers go without. n.b. 66% of flats in England have some kind of shared plot outside, although this may not be suitable for recreation, relaxation or exercise.
And what of London? Are there fewer private back gardens here?
It's been estimated that 24% of Greater London is covered by private gardens, by far the largest proportion of any UK region. But that doesn't mean residents have access to them... with residents of Westminster and Tower Hamlets particularly short-changed.
Key to London's garden shortfall is that a greater proportion of us live in flats than in the rest of the country. At the time of the 2011 census 50% of households in London were in flats. By 2014 it was up to 53%. That proportion might be nearer 60% today.
Making some whopping assumptions, let's say 20% of that 60% have a private back garden, along with 95% of the remaining housing stock.
20%×60% + 95%×40% = 50%
If so, that would mean London households split roughly fifty-fifty, half with private back gardens and half without.
And that in turn would suggest why so many Londoners are so keen to go out for daily exercise... it's because half of us can't do it in a garden at home.