Found it!

I knew it was there somewhere lurking outside the back door and sure enough, it was. You know those archealogical digs where entrepid explorers follow a tale of a lost city, hack their way through dense undergrowth, confront dangerous beasts and finally achieve their goal and emerge grimy but victorious? Well it wasn't quite like that.
I had it on good authority (Claire) that somewhere under the piles of bricks, wood, rubble and plaster lay the remains of our back garden.
A skip was duly delivered and the expedition was mounted to try and discover the lost garden of the Downings. You will be pleased to hear that local lore was right (as if the wife could ever be wrong) and indeed, by the end of a long and arduous day, we had found what was definitely the remains of our back garden, with the emphasis on the word 'remains'.
Dangerous beasts there were too. Claire had seen a rat the day before - fortunately I did not and moving a pile of insulation proved more difficult due to the bumblebees building a nest in it. They, plus a small amount of insulation ended up in a broken orange plastic bucket which now lives in a nettle patch just over the back fence in the allotments.
Now if they could just hurry up and take the skip away, I could park outside my house again...