Somebody really didn't want me to walk this stretch of the 140-year-old public footpath. But who is that person? Well, the land known as High Cross estate is registered to a company called Rarebargain Ltd. But on that land is a still-incomplete £40m mansion known as Hamilton Palace, which is being built for Nicholas van Hoogstraten, the man described this week in the papers as "the maniac in the mink". "Mink" because of the coat he likes to wear, and "maniac" because of his conviction earlier this week for the manslaughter of one of his business rivals.

The results of Van Hoogstraten's massive vanity project can be glimpsed once you rejoin Framfield nine. A gaudy, copper-coloured dome peeps above treetops. Somewhere in a vulgar mass is a 600ft gallery, lifts, bevelled pillars, and more en suite bathrooms than a rambler can shake a stick at. The palace includes a mausoleum that Van Hoogstraten hopes will house his mortal remains for 5,000 years.

It is this view that Van Hoogstraten objects to ramblers seeing. He hates ramblers, calling them "the great unwashed" and "riff raff". He was also reported as calling them "Herberts", but said he was misquoted: he had really meant to describe them as "perverts".

Yesterday, with Van Hoogstraten cooling his heels in jail until he is sentenced, this member of the great unwashed decided to plant his perverted size 10s where the millionaire doesn't want them. I rambled through the estate of an avaricious and ruthless businessman. That said, as Van Hoogstraten is notoriously vengeful and noted for getting butch men to throw grenades at people who cross him, I would like to add that by "avaricious and ruthless" I mean "lovable and good with children".

I was accompanied by Kate Ashbrook, who for the past four years has been the leading campaigner against the illegal obstructions erected on this land. She would like it to be known that she has found Van Hoogstraten "unfailingly polite and courteous". "This is the most famous blocking of a public highway in Britain," says Ashbrook. "But it is symptomatic of a much broader problem. One in four footpaths in England and one in two in Wales are blocked in some way - whether it be by crops, houses, golf courses" ... or a mausoleum for a man described by a judge as "an emissary of Beelzebub", by which he (one feels sure) meant "a man of refined taste".

Instead of leaving the road by the route designated on the Ordnance Survey map, we Herberts were compelled to climb over a stile in a fence further down the road. This stile and the subsequent diversion in the footpath have been erected following meetings between East Sussex county council and Rarebargain. When the diversion was published for consultation a couple of years ago, East Sussex received 5,000 objections, but those letters did not change the council's mind: it still supports the diversion.

The stile, as Ashbrook points out, would be quite difficult to climb if you had arthritis. But who cares about the rights of arthritic riff-raff when the privacy of a convicted killer (by which I mean "pillar of the community") is at stake? The designated diversion takes walkers away from Van Hoogstraten's estate. The old public footpath goes through a charming little oak wood and offers much more appealing views of the South Downs.

Ashbrook, who is chairman of the Ramblers' Association's access committee and general secretary for the Open Spaces society, reckons she has spent £30,000 of her own money in the legal battle to get the obstructions to the footpath removed. She has fought Rarebargain in court, and is currently embroiled in a judicial review with the county council over its failure to clear Framfield nine. After four years, the legal action hasn't achieved what she wants. "I just want to get the footpath cleared," she says.

In 1998, the Ramblers' Association realised that a barn had been plonked on Framfield nine on Van Hoogstraten's land nine years previously and took legal action to get it removed. Magistrates fined Rarebargain £1,600 and ordered the payment of £3,500 costs. But nothing happened - fines weren't paid, the barn wasn't demolished.

All was not lost. Ashbrook and other ramblers nurtured great hopes for an amendment to the Countryside and Rights of Way Act 2000, which gives magistrates the power to order removal of obstructions to a public highway by a fixed date. Section 64 of this act became law on January 30 last year. Two days later, on her birthday, Ashbrook went down to the High Cross estate to take photographs to show that the obstructions were still in place. As a result, in March, Rarebargain was found guilty of obstruction once more. Magistrates ordered that fence, gates and fridges be removed within 28 days, and the barn within six months. Despite later similar court rulings, the obstructions are still there; costs and fines amounting to £93,250 have not been paid.

But why hasn't the council removed the obstructions to the footpath as ordered to by magistrates? A couple of years ago it served notices ordering removal of obstructions within 90 days, but also said that if the company came up with a suitable diversion, it would put the notices on hold. This is today's bizarre situation: there are now two footpaths; the old, designated public highway and the new, dog-leg diversion, which is backed by the county council. This isn't good enough for Ashbrook. She took East Sussex to court for failing to do what magistrates ordered. But she lost. Her appeal will be heard on October 14, a few days after Van Hoogstraten is sentenced.

If she loses, there will be a public inquiry. The bureaucratic wheels turn obscenely slowly. Why can't some stout-calved and stouter-armed ramblers cut the red tape? Or snip through the barbed wire, pull down the other obstructions and restore the footpath? "Direct action like that isn't always a good idea," counsels Ashbrook, "though as a last resort it's something we shouldn't rule out. The police can arrest you for criminal damage, you see."

But they didn't arrest Van Hoogstraten for building a barn across a public footpath, nor representatives of Rarebargain for erecting other obstructions, nor ensure that fines and costs imposed on the company for failing to remove them were paid. "True," she says.

Yesterday, the High Cross estate was deserted. There was scaffolding rigged up on one tower but no builders were working on it and no security guards were to be seen. And the man who commissioned the thing is housed in rather less sumptuous apartments for the foreseeable future. Who now stands to gain from the blocking of Framfield nine? That's not obvious, but what is clear is how easy it has been for a rich bully to trample over one of the few rights ordinary Britons have. By "rich bully", naturally, I mean "countryside champion and sage".