My dream when I retired last year was the freedom to travel off-peak to public galleries, national monuments, gardens and other places of interest.

Naively, I envisaged enjoying these long-awaited treats in a peaceful, leisurely, unfraught fashion after being obliged for so many years to join the crowded throngs during weekends and school holidays.

But I’d forgotten about school trips. I am no spoilsport - I would be the first to advocate children’s introductions to any experience that is educational, enriching and life-enhancing. I have taken three and four-year-olds to Tate Britain and been astounded by the stunning tempera-painted cut-outs they have made after seeing Matisse’s “Snail”, and thrilled by their enthusiasm for plastering thick paint on boards with spatulas after Auerbach. We visited theatres, zoos, parks, farms and butterfly houses.

I’m now a regular witness to the downside of these excursions. No longer a participant in the school trip bubble, I’ve turned into an external observer frequently reminded of Burns’s lines: “O wad some pow’r the giftie gie us to see oursels as others see us.”

Probably they see me, if they notice me at all, as a grey nonentity. On the other hand this, without exaggeration, is how I have seen them. At Clapham Junction station I have been splashed with fizzy drinks, got chewing gum stuck to my mac and been bumped and jostled , while afraid that sparring juniors would knock each other off the platform. On the train, I have watched muddy feet plonked on seats while feats of acrobatic agility are performed on luggage racks and hand rails.

To get to the ladies in Kew Gardens, I have had to pick my way through a crouching horde of boys spitting paper gobbets at each other and flicking coins against loo doors. Last month at Hampton Court, focus on the Tudors was minimal as swathes of delicate buds were heedlessly trampled, and sweet papers, crisp bags and drink cans tossed to the ground.

The local swimming pool, where I go to fight the flab and soothe a chronic neckache exacerbated by years of perching on tiny chairs in a nursery classroom, is a nightmare of exuberant dive-bombers, who, despite my generous size, seem oblivious to my existence.

The noise in the National Portrait Gallery has been deafening; not just excited shouting, but piercing screeches punctuated by the loud thwacks of clipboards swiping heads. Interestingly, I now realise that a teacher’s noise tolerance threshold is many decibels above that of a “normal” person.

My threshold has dropped markedly since I retired.

There is no reason why we cannot all co-exist happily. But citizenship classes should include a compulsory element on how to behave on school trips; food, drink and sweets should be consumed only at designated times and litter disposed of properly; horseplay is inappropriate; consideration for other people and public property essential.

Schools could invite in members of the community to put their viewpoints.

Representatives of animal welfare groups could illustrate the hazards to animals of jettisoned litter, or council officials explain the process and cost of clearing and disposing of it.

Long may school trips flourish, but teachers must ensure that children cut the capers. Every school-supervised sortie should be capitalised on, not just for the educational benefits of the place being visited, but for the excellent opportunity to help children achieve responsible, social behaviour. Perhaps then, when they are out on their own or with their mates, I will not see them uprooting saplings in the local park or treating public transport like an adventure playground.

Gill Tweed recently retired as a nursery teacher in south London