The easiest way to understand escalators is to remember their alternative name of moving staircase. Thus, when you are on one, you can stand still, juggle or adopt whimsical ballet positions while the escalator conveys you up or down.

Each individual escalator moves in one particular direction and while young people may try to impress by running in the opposite direction, for the pensioner, this can be both embarrassing and injurious.

Tesco escalators are equipped with a disembodied voice advising you to “prepare to push your trolley off the escalator” and this particularly patronising instruction is best ignored or drowned out by singing heavy rock anthems.

Narrow escalators, such as those on many underground stations, can be extremely hazardous, especially if you’re being mistakenly pursued by armed members of SO19 or the angry busker to whom you inadvertently gave a coin from the Bailiwick of Jersey for her rendition of Vivaldi’s Four Seasons on an ocarina.

If you’ve had a stairlift installed in your home, don’t assume you can sit down on an escalator. Doing so may lead to you being trampled to death.