LET me apologise now to the couple I saw kissing so passionately at an open-air jazz picnic at the weekend.

Because I am about to expose them - or at least their scandalous behaviour - to 200,000 readers of The Northern Echo.

If either of them is reading this now, they might remember a few women strolling past them as they embraced at the back of Braithwaite Hall, near Ripon.

We giggled because they looked like a couple of schoolkids having an over-enthusiastic snog behind the bike shed - not the sort of thing you usually do in your mid-thirties.

They separated. She went back towards the toilet block. He walked just in front of us towards the dance floor.

"Let's see if he goes back to his wife," we joked.

I won't write anything which would identify them, because that would be callous, but what we saw next literally made our jaws drop.

The man did actually return to his wife or girlfriend. Then the woman he had been kissing came back and sat down right beside them, soon to be joined by her husband.

They were all close friends and were at the event together.

But the cuckolded partners obviously knew nothing of the deception we had just witnessed.

We couldn't help but watch this heartless betrayal unfolding in front of our eyes. This couple had inadvertently drawn us, and anyone else among the crowd of 800 who may have seen them, into their sorry saga.

I confess that on one level, we treated it as a bit of entertaining gossip. But it was also deeply disturbing.

The man - let's call him the Smug Stud - was overly affectionate towards his unsuspecting wife/girlfriend, constantly caressing her, while at the same time eyeing up his mistress. "He doesn't half look pleased with himself," said my friend.

The woman - let's call her the Devious Mistress - was cold and unresponsive towards her husband. Perhaps she felt guilty, but it didn't stop her pitifully making eyes at the Smug Stud on her left.

The deceived man looked uncomfortable, sad and bewildered and clearly knew something wasn't quite right. The wronged woman appeared oblivious. Sadly, we all knew something they didn't.

Perhaps the Smug Stud and his Devious Mistress wanted to get caught. Maybe the risk they were taking was all part of the excitement.

I'm hardly prudish. I know affairs happen all the time. But wasn't this behaviour - right under their partners and friends' noses - particularly base and soulless?

Isn't playing such cruel games with others' emotions and treating those whom you purportedly care for with such contempt simply wicked?

Reaction among our group was mixed. Some laughed, pointing out that it happens all the time. Others, particularly those with young children, found it unsettling. "It's so sad," said one mother. "It makes you feel slightly vulnerable, threatened, because you think of what could happen, of what you could lose."

One friend who has quite a racy social life said: "When you go out you see it all the time, it really is in your face. What you saw is just the tip of the iceberg and, as always, those being deceived are the last to know."

Should the Smug Stud and his Devious Mistress be reading this, I urge them to come clean to their partners. Because their partners clearly deserve better.

And the Smug Stud and his Devious Mistress really do deserve each other.