Most supermarkets now provide a range of shopping trolleys to suit the particular requirements of various types of customer, including those with seats for toddlers, mounting brackets for self-scanners, personalised number plates and built-in cross-trainers or treadmills.
Although there is an unwritten code on the use of trolleys – always push in an anti-clockwise direction, always overtake on the right, always wheel into free-standing displays of dog biscuits – the Geneva convention gives pensioners the absolute right to disregard all of these and push their trolley in any manner they like.
In general, this means you can push it very, very slowly, park it in the middle of aisles, on top of the fish counter and sideways across the top or bottom of an escalator. Having separate trolleys for fruit and veg, frozen food, dry goods and electrical items is also allowed, though manoeuvring more than a dozen trolleys tied together with string (see Knots) can be difficult and may lead to considerable damage in the wines and spirits section.
Placing your trolley on the moving belt of the checkout is only allowed if there is a queue of more than two non-pensioners, and you may also use your trolley to batter down the door of any toilet cubicle occupied by the under-thirties.
The convention reaffirms your right to leave your trolley anywhere in the car park, including in the middle of the shrubs, protruding from the passport photo booth and on top of any unleaded petrol pump on the garage forecourt. However, you are not allowed, under any circumstances, to use a trolley to imprison political prisoners, launch an offensive against a sovereign nation or transport nuclear weapons through a built-up area after dark.