Dear Mary | 31 March 2012

Q. How can I road-test a potential lodger? I am under pressure from old friends who know that I live alone and am away a lot, and also that I have a spare room with a bathroom in my central London flat. They all seem to have children who cannot find anywhere affordable to live in London. I feel that it would be selfish not to let the room, but what if the young person turns out to be uncivilised? I have no children of my own, so I am probably out of date, but I still expect a bit of deference from someone 30 or more years younger than me. I am nervous of being landed with someone whose parents insist that they are meek and compliant, but who will bring people back, throw all-night parties etc. Most of all, I don’t want to fall out with the parents by falling out with the child. Any suggestions for filtering out the wrong ’uns, Mary?
—Name withheld, London SW7

A. Trick the mothers into revealing the teenagers’ true intentions with the following technique. Say that you have not yet decided whether to let out your spare room, but that you know of another being rented out affordably by a neighbour of yours. But how would the teenager feel about the conditions, i.e. not having hordes of people back, being immaculate and keeping a low profile? The wrong mothers will become indignant, expostulating that their teenager is only human and would expect to party or throw their weight about, especially if they are paying. The right mothers will retort that their teenager would be lucky not to be living in cardboard city and would certainly be fastidious and keep their head down. You will then know how to proceed.