There had to be...yes...there! John hurried down the block and across the street to the CCTV camera. Looking straight into it, he said, very clearly,

'Sherlock's going to steal the Queen's handbag.'

Then he stood there, idly humming and mentally counting down. Ten...nine...eight...seven...

A black town car pulled up in front of him without even the slightest squeal of breaks. The rear door was thrown open, and Mycroft stepped out, umbrella in hand and a distinctly unimpressed expression on his face.