The Derren Brown method of confusion/distraction works well.
When they approach and give it the old "Got any spare change mate?" just respond with something like..
"But my garden wall is much shorter at the front" shrug your shoulders and wander off.
When they approach and give it the old "Got any spare change mate?" just respond with something like..
"But my garden wall is much shorter at the front" shrug your shoulders and wander off.