WHO says you can’t teach an old dog (and a smug one at that) new tricks? For instance, last week in Kidlington I saw a sign outside its village police station advertising a ‘Defensive Planting Exhibition’.

Admitted, I first saw this at 6.30am, an excruciatingly early hour, so didn’t take it too seriously until I saw the same sign 12 hours (and three Black Russians) later.

This time puzzled but satisfied by the authenticity of the exhibition, I wandered home, conceitedly entertained by fantasies of Triffids and Alan Titchmarsh forming a ‘thin green line’ round the village to deter Oxford’s criminal element.

But later, at home, I Googled the term and realised it is in fact a serious botanical strategy designed to hinder the urban burglar.

Indeed, as you read this, those aged 60 and over will already be shaking their heads at my horticultural ignorance.

And I guess I deserve it since I’d never realised that shrubs and bushes could be so useful. So practical. So threatening...

For those like me who, until today, had no inkling of the deterrent evergreens and perennials provide, here is a quick guide to how best to turn your home into a floral fortress.

First, plant any of the following – Creeping Junipers, Chinese Jujubes, Firethorn and any type of bramble (although as Wiltshire Constabulary points out ‘we cannot guarantee that the plant you buy will produce thorns’).

Nevertheless, assuming you are green-fingered, it should put potential burglars on their guard since they too are now au fait with all matters relating to horticultural security (‘criminals know that a small item of ripped clothing or blood can help the police identify them’).

Surprisingly, ponds and water features can also provide effective barriers, although I personally fail to see how an ornamental pond can scare off a potential intruder (having said that, if I was up to no good in a stranger’s back garden, a collection of assorted fishing gnomes might just elicit the required response).

What is surely no great surprise to anyone, however, is how menacing gravel can be.

Obviously, thieves don’t like to be heard, so a gravel bed anywhere – but particularly one say 100ft long and wide and preferably portable – should do the trick.

All of the above are tried and tested methods for halting the spread of crime, but having given this some thought, might I also suggest the following: 1. Invest in an army of highly-strung cats starved of shameless pampering; 2. Leave out life-size cardboard cut-outs of caravans; 3. Convert gardens into creches and hire toddlers to play without having to put away their toys come evening; 4. Deck gardens with all-year festive displays of laughing santas, jiggling snowmen and reindeer which glow.

Because let’s be frank, If it curbs crime, who cares how it looks?