Discussing with an Aussie on Bigcricket how people get started with spin bowling, I mentioned that kids will often turn up at a club having never 'Bowled' a ball, to be honest, some of them hardly ever have thrown a ball! He then asked about the sizes of our gardens...
So the images here are where I live. It's probably typical of suburban areas around London and other big cities with houses built from the 1960's onwards. Probably earlier? Any post-war municipal housing projects are likely to have been designed with small gardens. For instance (Post war) one of the biggest municipal housing projects is just up the road from me in Dagenham (see the link). As with my estate where I live in Basildon, Essex... a 1970's 'New Town', the gardens are barely big enough to swing a cat. If you look below you can see the size of the cars in comparison with the gardens. My garden is probably 20' x 20' and this is not unusual here in the UK.
My garden is ringed below in the images. The bigger ring is 'The Paddock' an area of grass at the edge of the estate which is big enough for my sons and I to drag a roller and a mower over to in the Spring and maintain a practice wicket on.
To be honest this is probably the only place and example of anyone in the UK doing such a thing, but I have had the blessing of the council before and they're more than happy that I do it and besides we maintain the hedges and prevent them from growing over the grass and shading it.
This shot is the same area, but a wider shot with the local football pitch. But, yeah if you're an Aussie, just have a look on Google earth/maps and looks at towns like Basildon, Peterborough, Dagenham, Milton Keynes or Harlow, all big new towns and check out the sizes of the garden plots.
So, you can probably see, this factor combined with the fact that from Nov through late march, weather-wise it is pretty bleak. Kids are more likely to play football here in the UK especially kids from these areas as Football is culturally embedded into our society. I think most working class people see cricket as being Middle Class, if they've never been involved in it. So in answer to the blokes question, yeah you're right, it would be very rare for kids to play cricket in their back yards. It's rare for kids to play cricket full stop!