This is a very difficult piece to write because it is so personal and directly concerns my family. It was inspired when I read an innocent comment, made in a jokey self-deprecating way, about someone making a mistake. The comment was, simply, "I must be a retard". It stopped me short with quite a jolt.

It brought back memories of a beautiful day at the end the summer holidays a few years back. We decided to have a rare family outing on the boats and visited St. Martins, one of the off-islands. When you live in a tourist area, you rarely visit those places that visitors rave about because your daily working life always seems to get in the way. This was a conscious decision on our part to step into the shoes of visitors and just enjoy the islands.

It really was a glorious early September day. The sky was clear blue dotted with the barest handful of clouds, the breeze was light and the sea was a myriad of greens and purples reflecting the sunlight in sharp little sparkles. The island of St Martins lay long and low, patchworked with small green and brown fields, its white sand beaches dazzling in the sunshine as the boat slowly approached the quay. My husband and I both carried rucksacks packed with a picnic, several towels, swimming costumes and all the other paraphernalia that families tend to take on days out. Our fifteen year old son, taller than me now, led the way up the quay. Following him was our daughter, thirteen year old Joy, excited and skittish, her fair hair tumbling out from underneath her sunhat. Most of the day visitors headed off to the left but Joy led us straight to the public toilets on the right, probably a sensible stop before a long coastal walk! The other day-trippers were all gone when we emerged and headed off along the path.

It was so lovely to be a family and enjoy a day out. We always seem to be doing so much independently of each other that time spent together is very precious. We also have to be careful to pick a 'good day' for Joy if we can. She has been diagnosed autistic with learning disabilities in various stages over the past thirteen years and can become very 'stressed out' when she finds that she cannot handle a situation. You never quite know what is going to trigger off a 'tizz' or when it will happen. Sometimes you have to watch what you say very very carefully in case she takes offence at one word and gets upset.

We ambled round the coastal path for a couple of hours, enjoying the views and the warmth of the sun on our backs. Then we stopped for lunch on a white sand beach where seagulls on nearby rocks surveyed our picnic with beady-eyed hunger. Joy kicked off her trainers and socks before dashing down to the water's edge to paddle in the cold clear water. Soon she was splashing her brother and he was splashing her back. It was so nice to see them interacting like that, quite often they are indifferent to each other - more like 'ships that pass in the night'.

We called them back for lunch - sandwiches, crisps, chocolate biscuits (a bit melted but still tasting great!), apples, grapes, bananas and pears, lots of orange juice and coke for the kids, flasks of coffee and tea for us. Then we all relaxed afterwards - or rather three of us did, because Joy was off down to the water's edge again, pulling up seaweed, throwing pebbles into the sea, splashing herself and shrilling her delight. She's a free spirit and being hemmed in just doesn't suit her loud, boisterous, exuberant nature very much. She's in her element outdoors where she can make (almost!) as much noise as she wants and get wet or mucky (preferably both!).

Early afternoon saw us packing the picnic stuff back into the rucksacks, slapping on some more sun-cream, drying feet and putting shoes and socks back on. Then we ambled along the coast path on the other side of the island, watching the brightly-painted fishing boats come chugging round the eastern headland on their way back to harbour on St. Mary's. We stopped for ice creams at the shop and arrived back at the quay licking them as fast as we could because they were melting so fast in the sunshine!

We only had ten minutes to wait and Joy, tired by now, sat beside me on the bench, her blonde head resting on my shoulder. The turquoise-green boat came into view, her white wake streaming out behind her on the calm sea as her skipper skilfully approached the quay. We grabbed our rucksacks and headed down to meet it along with about fifty other people who had been scattered across the nearby beach and dunes. Joy's tiredness was making her rather tetchy by now and she stamped her feet on the concrete quay, impatient to be on board and on her way home. I tried to soothe her but she was becoming noisy and agitated. In fact, she let out a couple of piercing shrieks "no boat! no boat!" when I said we would soon be on the boat. (She can be very contrary when she's upset.....)

At that point, two elderly couples behind us were openly staring at her and one gentleman turned to his friends. "She's obviously retarded," he said somewhat scathingly, oblivious to the fact that his deafness made the loud comment audible to almost everyone in the queue. It was horrible. Everyone suddenly had something that needed their immediate and concentrated attention. Both my husband and son went red with embarrassment. I very nearly gave way to the urge to turn round and bawl him out. But he was of a generation that was accustomed to using terms like 'retarded' and 'mongol' so it probably wouldn't have served any useful purpose. His ideas about what are now called 'special needs children' were carved back in the stone age and he wasn't going to change.

But it made me feel very cold and sick to have my unique and beautiful daughter described in such a dismissive and disparaging way.

Fortunately, the boatmen had got the Lily of Laguna securely berthed at the quay and were beginning to hand people carefully down the steps into the boat. So we were saved any more of Joy's agitation - once she was moving again, she was fine. The elderly couples took a seat conspiciously as far away from us as possible at the bow of the boat. We headed for the stern so we didn't need to overhear any more of their cruel and thoughtless comments.

Joy leaned over the side of the boat as it bobbed over the waves on the way back to St. Mary's. She was happy and smiling, watching the creamy wake curl back from the bow, and singing quietly under her breath. I noticed that a few people gave me sympathetic smiles during the half hour voyage but there was a slightly humble ruefulness to them that told me they didn't understand Joy's problems either. It spoiled the end of our day and we were all rather quiet on the walk home (except for Joy of course!).

So, please think before you say something about a misbehaving child, however young or old they might be. You have no way of knowing if that child is autistic or disabled in any other way. The most cruel aspect of autism, in particular, is that the affected child LOOKS perfectly normal. In fact, they are often beautiful, other-worldly children and so naturally attract the attention of other people before their odd behaviour is noticed.

You don't need to understand anything about the child's medical diagnosis, but I beg you to show more sympathy and tolerance than this elderly gentleman showed to us and our daughter.