In the old days, the most voters saw of the Downing Street garden was the formal photo of the cabinet, all blokes, lots of moustaches and waistcoats, not many smiles. Then someone realised a televisual political asset was being wasted.
Behind those high walls, visible from Horse Guards Parade, it's actually the size of a decent L-shaped suburban garden – albeit one overlooked by a lot of neighbours in Nos 11 and 12; and by even more security.
There's a terrace with steps, leading from cabinet room level down to the garden, which has a cottage-like, slightly chaotic style – English picturesque. In nice weather PMs can schmooze allies or flatter potential foes while a nice breeze cools their afternoon tea or evening G&Ts.
Sarah Brown grew veggies there and the Blair boys played football. You could imagine a nice family picnic on the shaded lawn, generous flower beds to hand, but definitely no sunbathing. The thought of that IRA mortar which landed in the garden in 1991 – missing its target, John Major's cabinet, by just 40ft – would be enough to put anyone off. It created a 4ft crater.
It was Major who first used the garden to full effect on a sunny day in 1995 when he used it to announce – quite unexpectedly – that he would be resigning the Tory leadership – though not the PM's job or house – to fight any challengers. It went out live on TV and stunned Tory MPs.
Blair must have clocked the moment. Not long afterwards he used what began to be referred to as the "rose garden" – shades of the White House's al fresco press conference venue – for a joint appearance with his then-favourite president, Bill Clinton.
Now, with the new emphasis on open-necked informality the garden is more popular than ever. On Thursday it was the backdrop for Cameron's remarks on the Cumbrian shootings, but the new prime minister first used the garden to unveil his coalition partnership with Nick Clegg. Fortunately the two looked to be roughly the same height on TV. Downing Street's perfectionist gardeners might otherwise have been tempted to prune the taller one.
