MR David Leyshon of the Ramblers' Association, in a letter to this paper on October 20, said that readers should ignore my scare-mongering and misleading regurgitation of inaccurate and speculative press reports.

He was referring to my brief notes about the recent and devastating outbreak of swine fever in Norfolk which, at the time of writing, had already cost the pig industry an estimated £20m.

Some 35,000 pigs throughout Essex, Norfolk and Suffolk had to be destroyed, and the outbreak was found to have started in a sow on a pig farm at Quidenham in Norfolk. That farmer's entire herd of 1,750 pigs had to be slaughtered.

A meticulous investigation by Ministry of Agriculture, Fisheries and Food experts concluded that a Far Eastern strain of the disease was responsible and a ministry epidemiologist, Mr Hugh Morris, is quoted as saying that a thorough investigation of more likely sources, such as pig, vehicle and people movements, showed that the only way the Far Eastern strain could have entered the pig herd was through consumption of a processed meat product.

Mr James Black, the vice-chairman of the National Pig Association is also quoted as saying: "It's very worrying that it looks like it was caused by an imported pork product."

Mr Leyshon accepts that prognosis and says so in his correspondence. I am not sure why he has written such a strange letter, however, nor do I understand why he believes his sources are any more reliable or authoritative than mine.

I do find it disturbing that he condemns my right to free expression, the airing of one's opinion and the need for informed speculation. His letter smacks of worrying authoritarianism. I presented the well-publicised and equally well-considered theory that the processed meat product in question could be a ham sandwich which had been discarded by a rambler.

Careful scrutiny of my words will show that I wrote " ... scientists have concluded that it (the processed meat product) was probably a ham sandwich which had been thrown into the compound by a rambler; it might even have been deliberately fed to the pig."

The word probably was used quite deliberately by me because MAFF experts could not prove that the product was a ham sandwich, and so I am baffled as to why Mr Leyshon has reacted in such a bizarre way. I did not state that the product was a ham sandwich, nor did I state it had been thrown by a rambler - I merely raised those possibilities. What is wrong with that? Is one no longer permitted to speculate on the cause of something as catastrophic as this outbreak?

According to my sources (which include The Times and the Yorkshire Post, neither being noted for publishing misleading reports), Ministry of Agriculture officials did say the discarded sandwich theory was a probable cause of the outbreak and, I quote "because the sow was kept in a paddock close to a path popular with walkers."

I have another quote by a MAFF spokesman who confirmed: "The pig that first came down with this was in a field close to a public footpath. The most likely scenario is that it was caused by an infected pork product discarded by a passer-by."

The owner of the pig farm in which the outbreak started, Mr Jeremy Havers, is also quoted as saying that the proper footpath near his pig unit is overgrown, which leads ramblers to make use of a track which passes between groups of sows.

Only two strands of electrified wire separate the sows from the path, so it is easy for anyone to toss a piece of ham sandwich into the compounds. It was he who pondered the likelihood that the "processed meat product" had been deliberately fed to the sow.

Normally I ignore Mr Leyshon's outbursts, but I felt this one should be given a further airing. If I am guilty of an error, then it might be that I have followed the theory that the processed meat product was a ham sandwich. After all it could have been a pork sausage. Whatever it was, how did it get into that pig compound near the public footpath?

I am sure readers will make their own judgements while ignoring Mr Leyshon's letter.

Ramblers' tales

On the subject of ramblers, I must make it clear that I am not antagonistic towards them. After all, I am a rambler myself, thoroughly enjoying my exploration of public footpaths throughout Yorkshire, Durham, Northumberland and the Lake District, either with my wife or with a group of friends.

However, I have no wish to invade private property, I do not leave a gates open or drop litter, I do not let my dog roam off the lead among livestock and I obey the country code. I do love and respect the countryside and those who live and work there. However, I am realistic enough to know that some ramblers do not behave in an acceptable manner and some dislike landowners - after all, no-one is perfect - but the majority are thoughtful, kind, considerate and welcome to enjoy our landscape.

Others, however, do provide me with wonderful material for my stories, both in fact and in fiction. (Have you read any of my 105 books, Mr Leyshon? You may find some delightful rambling stories in them!)

Here are two from this year's encounters. Having driven to Whitby for a book signing session, I decided to return home via Eskdale, Rosedale and Hutton-le-Hole. As I motored from Chimney Bank Top at Rosedale towards Hutton-le-Hole, it was such a lovely evening that I decided to stop for a short walk.

As I did so, another car pulled on to the verge some 200 yards away and two people climbed out. I did likewise and realised the couple were hailing me. As I went towards them, I saw they were clad in walking boots and sensible clothing, and they bore a map. Then the man asked if I could help him and I said I was delighted to be of assistance. He then asked if I could tell him where he was. I said: "You're on the road between Rosedale and Hutton-le-Hole." "Could you show me on my map?" He handed it to me. When I examined it, I said: "I'm sorry, but this is a map of Northumberland." "But this is Northumberland!" he snapped. "No," I said. "This is the North York Moors, you're in North Yorkshire." He was rather cross and said he was supposed to be in Northumberland.

I did try to guide him back to a road which would take him there, but I don't think he believed me. I'm sure he thought I didn't know where I was!

The second tale happened one Sunday when I was repairing a boundary wall of my garden.

As I was preparing it for pointing, I became aware of voices and when I looked up, four ramblers - two men and two women, all in middle age - were coming down the field immediately opposite my home. As they grew closer, I could hear they were angry about a blockage at the point where they had entered the field (a public footpath does run across the top of the field, outside its boundary fence), and they became even more agitated when they reached the gate opposite my house.

It was padlocked due to problems with tourists, so they had to clamber over it to leave the field. They then stood near me, grumbling and groaning about their experience, then made as if to go down a driveway next to my house. "Can I help?" I asked, realising they were lost. "This is a public footpath?" one of them asked, indicating the drive. "No," I told him, "it's a private drive. And there is no public footpath in that field, either. You've misread your map - you should have emerged quarter of a mile up that hill ... I do hope you haven't damaged the fence that farmer erected to keep deer away from his plantation of saplings."

How on earth they managed to gain entry to that field is something of a mystery but I gained the impression they thought I was being obstructive. I do not know whether they were members of the Ramblers' Association, but I do know they qualified as members of the Grumblers' Association.