LONGLEAT was living up to its lusty tabloid image this week. In the grounds, within hailing distance of the magnificent Tudor house, there was sexual activity going on; rather loud and unabashed activity at that. The press photographers, with their telephoto lenses stalking the grounds hoping for a glimpse of the new owner of the place - the former Viscount Weymouth, a man known by the popular papers as the 'Loins of Longleat' - need not be too disappointed that they missed it, however. These were lions at it.

'Oh, oh, porno shots,' said Roger Cawley, general manager of the estate's safari park. He was, at the time, doing something no day-tripper would be allowed to do, leaning out of the car window and pointing at the pair of noisily coupling lions. 'Won't do that old boy any good though. He had a vasectomy last year.'

On Wednesday, the day after the Marquess of Bath died, Longleat was open as usual. Postman Pat's Village, the Dr Who exhibition, Oscar's nightclub, the Adventure Castle, Pets' Corner and the safari park were all admitting paying customers.

Lord Bath had intimated that things should carry on without him; business was more important than sentiment. His business was preserving the house and the estate, his inheritance. He dreamt up more imaginative ways to do it than any landowner before him: in 1946 he was the first historic house owner to open his house to the public; in 1966 he introduced lions to the grounds; in 1992 he gave his heir permission to build a holiday village within its broad acres.

The only sign of mourning on Wednesday was the union flag at half mast atop the house. And inside, upstairs, along a corridor that had been converted into a suite of offices to house the many staff required to keep the operation in action, Lord Christopher Thynne, the marquess's youngest surviving son, was dressed entirely in black.

Behind his desk (the sign on his door reads 'Charming, Considerate Chris in Control'), Lord Christopher was wearing a black shirt, black leather trousers and black cowboy boots. A black leather motorbike jacket lay on a pile of books on the floor. He had a black leather-bound cigarette lighter hanging from a lace around his neck, and a collection of fearsome keys and penknives jangling from his belt, jailer-like.

'My father always used to say the house owned us,' he said. 'We daren't say anything rude about it. I don't think I really realised how important the place was until I became an adult. Mind you, I don't think I became an adult until I was about 54.'

Lord Christopher, who is now 57, is the controller of the house, its curator. While his father was alive, his was the task of keeping it in order. He was at his post until his brother returned from holiday in St Tropez. He said he had no idea if the new marquess would want him to continue.

'It would be perfectly tactless for me to say anything about the house's future,' he said. 'That is entirely up to my brother now.'

He would, however, cheerfully talk about his role in the past.

'I suppose one should have a budget, but one doesn't. How much would it cost to put the place right? Well if somebody gave me a million I could spend it. But not all of the work I'd spend it on is absolutely urgent.'

The recession has not been kind to Lord Christopher and his attempts to keep the place viable. Numbers paying to look round the house in 1991 were down by about 15 per cent on 1990. This year he expects them to be down by another 7 per cent. He has had to find other ways to augment the income from visitors. In the last month he has rented out parts of the grounds to half a dozen events, including a radio hams' convention and a rave, an all-nighter in a marquee up in the woods. One of his most lucrative exploitations of the house is to hire it out as a movie set.

'The silly thing is I can never remember the names of the films they've made here,' he said. 'We had one recently, what was it called? Oh God, how rude of me, I've forgotten. Never mind, they've paid their cheque. And the other day this chap came down to recce for a film with that cannibal fellow in it. Hopkirk is it? I asked how long he wanted, two or three days is the usual. He said about six weeks. Now that would be marvellous.'

Most visitors to the house apparently love it when the crews move in.

'We had a film here with Trevor Howard in it,' remembered Lord Christopher. 'And I met this party of old dears who were just thrilled that he had walked

past them earlier in the day. 'He was such a nice gentleman' one of them said. Which was odd as he was the biggest shit you could imagine. And I hadn't the heart to tell her he wasn't actually on set that day.'

Although not many, there are some money-making enterprises Lord Christopher would not contemplate in his fight to keep the place going.

'The Duke of Bedford used to have people for the weekend, who paid a fortune and pretended they were his guests. Nothing could be worse than having 20 Americans . . . no, why be rude to Americans . . . 20 foreigners - because they're the only ones who can afford it - hanging around all bloody weekend. Be a hotel, fine. But don't pretend they're your guests. It's embarrassing.'

And one thing he could not do is sell any of the contents of the house. A complex trust arrangement, designed to circumvent the ravages of death duties, means that anything sold is taxed at 90 per cent.

'The Sunday Times always has my father in that list of richest people. This year he was supposed to be worth pounds 250m. We were surprised because he'd apparently lost 110 million quid since the previous year, which was careless of him. God knows where they get these figures.

'You know how much money he actually left? About pounds 200,000. I suppose they're estimating the value of the contents of this place, but that's all paper money, you can't actually sell anything. And anyway, if they were doing that, they got it wrong. I reckon it's worth pounds 500m at least.'

Walking round the house, it is not hard to accept that figure. You are confronted round practically every corner by a Tintoretto, a Titian, or the original Tardis. The paintings are astonishing. The grand staircase is lined with huge scenes of death, paintings called A Lion Hunt, A Bear Hunt, Hawks Attacking a Heron.

The style might be described as eclectic, priceless antiques jostling for space with hunting trophies. In the grand hall there is an elk's head on the wall, its antlers spreading wider than the wingspan of a light aircraft. On the floor there is a lion skin hearth rug. It is unclear whether this is from a locally culled animal.

Dotted through the rooms, charming, talkative women guides sit on high stools, waiting to engage visitors in conversation. They are so polite they say things such as 'Can I be beastly to you and ask you not to touch?' to small boys fingering pieces of Cantonese porcelain. On Wednesday, the guide in the state saloon spotted a group of teenagers staring at a Bath family wedding photograph.

'Everyone looks so grumpy because that's Queen Mary in the middle and she really was a rather frightening woman,' the guide explained, in the rich tones of a Fifties radio announcer. 'I think that was because she was German.'

'Ve are German,' said one of the teenagers.

'Oh, my dear, I'm so awfully sorry,' came back the guide in a way which made it unclear if she was apologising or commiserating.

Like Lord Christopher, many of the staff around Longleat expressed uncertainty about the future. Lord Weymouth famously did not get on with his father, nor his brother, and left them to run the place. He did not get involved, except in occasional grand designs such as building the biggest maze in the world and inviting Center Parcs to build a holiday village in the grounds (a project of which, despite the rumours, his father apparently approved). Now he will be in charge. The staff don't know what to expect. 'I just don't know if I'll have a job tomorrow,' said one elderly retainer.

Over at the safari park, past the lake filled with hippopotamuses and sea lions, past the gorilla island where the apes have a television set to keep them amused (they particularly like TV-am) Roger Cawley said he would miss the marquess enormously.

'He was a marvellous man,' he said. 'He'd come here practically every day and check his trees. He loved trees. He'd say to me, 'you've let the bloody elephants at my trees again' and jump out of his car and run over with a paint brush and dab some preservative on the spot where the elephants had barked a tree. His son, we never really saw. But he's a commercially minded man, I'm sure he'll leave things as they are.'

It may not be as popular as it was when it first opened, but 350,000 people visited Longleat's safari park last year, watching the tigers, rubbing shoulders with the giraffes, having bits of their cars removed by the monkeys. Twenty-five years after the marquess dreamt up the idea, people still like to see animals in a bit of space, with grass rather than concrete under their feet. And unlike London Zoo, the park remains profitable.

'We give the lions three sheeps' heads each a day, costs about a quid, less than it costs to feed a domestic cat,' explained Roger Cawley. 'The hippos we don't feed in summer, they graze a field. And the sea lions are fed by the visitors, who buy little pots of fish. So they don't cost anything. I don't understand how London Zoo, with a million visitors a year, manages to lose money.'

Lord Bath's legacy is that he started an industry, gave a blueprint for other historic house owners to survive the 20th century. It is a blueprint that, despite all the rival attractions of the Nineties, still seems to be - just about - working.

'Actually, I think the saddest thing about his going,' said Lord Christopher, 'is that we've lost a natural gentleman. But it's true he did invent an industry. Shame the others followed. Competition is great for the public, but bloody hell for us. Once we were the only house open to the public. God, it would be marvellous if that were still the case.'

(Photographs omitted)