In September 1939 three things happened – war broke out, we started at Ilkley Grammar and they let girls into the school for the first time. I don't think they were connected in any way," says Teddy Leteve with a smile on his lips and a twinkle in his eye. The sprightly 79-year-old is one of a group of old school friends who have been meeting up for biannual reunions for the last six years.

"I came for the first time last year," says Teddy. "I got a phone call one Sunday evening from someone I was at school with," he says gesturing towards my father Patrick. "It only took him 63 years to get in touch!" Teddy says he will be a regular attendee now. "It's strange," he says, "you are at school for just a few years, but the friendships you make are really quite intense and important."

He admits it was rather strange when he arrived at his first reunion. "I looked around and I thought to myself 'who are all these old people?' Then you get talking to someone and you start to recognise the young person they once were."

The reunions are organised by Arthur Smith – one of the younger members, at only 75 – who got in touch with a fellow Old Olicanian on an impulse nine years ago. "I bought a new computer when I retired and with it I got some free software which had a UK telephone directory on it. So I tried out a couple of names. Eventually there was a small group of about seven of us and we all met up."

After that first meeting, Arthur, who now lives in Brough in East Yorkshire, suggested contacting other former pupils in different year groups. "When you are at school, you tend to know the pupils who are in the years above you and so when I contacted the Ilkley Gazette to invite others, I decided to open up the reunions to anyone who had been at the school in the fifth or sixth form between 1947-50."

Soon the word spread. "There is usually a group of about 30 to 40 who turn up to each reunion and we see a couple of new faces every time," says Arthur. It's quite an achievement. It's clear as an onlooker that everyone has a wonderful time at these get-togethers. Inevitably there is a lot of reminiscing, but there is often quite a bit of catching up to do as well.

"It's interesting to find out what path people's lives have taken," says Arthur, "but that sort of thing doesn't necessarily come up in conversation; it's about renewing old friendships, not making comparisons or judgments."

There's an Old Olicanian who flies over from Portugal from time to time and at the reunion I attended one woman, Brenda Hill, had travelled from Canada.

"This is the second reunion I have been to," she says. "I was quite nervous the first time because I wasn't sure anyone would know who I was, but it was really uplifting to see how pleased people were to see me. Schooldays were a really great time."

What is most remarkable – and affecting – about this group is to see the shadow of their childhood selves emerge as they chat enthusiastically about their school days. The war didn't seem to impact too much, although that was partly to do with geography. "Ilkley didn't get any bombing," says Teddy, "but there were bombs nearby. I remember because I was away for the weekend visiting relatives and I missed it. I was really disappointed!"

The target was Low Mill at Addingham which had been a velvet mill owned by a German family called the Pelzers. When war broke out, they moved back to Germany and the mill was taken over by the Ministry of Defence for war work. "Nobody knew," says Teddy, "but they were manufacturing SU carburetters there." The Germans dropped several bombs in the vicinity of the mill, "but they didn't do very well," says Teddy. "One dropped on the wall of a house at Beamsley – the poor chap had moved out of Bradford to escape the war and they dropped a bomb in his garden – and another landed on the cricket pitch at Bolton Abbey." Leeds Modern (now Lawnswood School), was evacuated to the grammar school at Ilkley. "They would have lessons in the morning while we did games or homework and then we would do a swap," says Teddy.

"They didn't stay for long though. Leeds wasn't as badly bombed as Bradford and Sheffield, so they decided to go back to the city and take their chances."

Some European refugees also arrived, Jewish families who were fleeing the Nazis. "There were the Rummelsburg brothers from Germany," says Teddy, "and a Hungarian lad called Varga."

Since all the young men were away fighting, the teachers were all either women or older men, masters who were kept on beyond retirement age. "There was one old chap we used to call 'Chuff' Evans because he made a strange, snuffling noise when he spoke," recalls Nigel Wormald, a keen schoolboy cricketer. "There was a rumour that he had been gassed in the First World War and only had one lung."

Zita Fleming (née Carter) remembers knitting socks for soldiers, British officers staying at the Royal Hotel on Wells Road, Canadian soldiers billeted around Ilkley and Italian prisoners of war in Otley. "The prisoners helped to build Valley Drive," she says. "We used to ride past them on our bikes to have a look at them. We thought we were being very brave, but they were never any trouble. In fact, quite a few of them stayed on after the war and married local girls."

Today we worry about lack of exercise and obesity in young people. There were no such worries for the class of '47 – this was the pre-television generation and they were never short of things to occupy them, physically or intellectually.

"There was always something going on after school," says Marjorie Jackman (née Jackson: "I swapped a 'son' for a 'man'").

There was cricket and rugby for the boys and netball and hockey for the girls. Every evening there was an after-school activity – choir, debating, drama, chess and the student Christian movement were just some of the clubs and societies on offer.

"There was never a dull moment; I loved school," says Marjorie, who was there from 1940 to 1947 and in 1963 was the first old girl to become a governor. The school has a long and distinguished history – it celebrated its 400th anniversary last year – and it is obvious that these old boys and girls are proud of the part they have played in that history. "It was a real privilege to go there," says Marjorie. "It was the centre of our universe," adds Brenda from Canada.

The artist and poet Derek Hyatt, who now lives in Collingham, agrees. "We were jolly lucky," he says. "The teachers were all excellent; I was particularly inspired by Tommy Walker who was the art teacher. He was a beacon of culture, very knowledgeable about music, art and literature. It was Mr Walker who first took me up to Langbar Moor to do some sketching and I still come back most weeks to draw up there." It was also on Langbar Moor that, as a youngster, Derek found some interesting 'souvenirs'. "We boys always used to go up there to try and find bits of used ammunition because the Home Guard practised up there – and there were a couple of plane crashes on the moor as well."

On one occasion, Derek had been up on the moor and found what he thought was a dummy hand grenade buried in the mud. "It looked like one that my father used in the Home Guard," says Derek. In fact, it was a live grenade, the pin had been pulled out and the only reason it did not explode was that it was caked in mud.

"I cycled all the way back down from Langbar Moor with the grenade bouncing about in the basket on the front of my bike," says Derek. When he got back to Ilkley, he was stopped by the local Home Guard captain who asked him what he had in his basket.

"When he saw the grenade," says Derek, "he said, 'just prop your bike against that lamppost and we'll call the bomb disposal unit'."

At morning assembly the next day the headmaster explained that someone had brought "something dangerous" into town the previous evening and asked that anyone who had any such souvenirs bring them into school the following day without fear of reprisal.

"When we got to school the next morning, the entrance looked like an armoury!" laughs Derek. Another of his moor finds was a magnesium flare, which came in handy when the town was celebrating with fireworks on VE day. "I set it off in our back garden and it lit up the whole of Ilkley," he says, with a smile. "Mind you," he adds, "it also burnt down our summerhouse."

The reunions are held on the first Wednesday of April and first Wednesday of October at the Generous Pioneer pub in Burley-in-Wharfedale. Anyone who was in the fifth or sixth form at Ilkley Grammar School between 1947 and 1950 is welcome. Contact Arthur Smith on 01482 668780.