Property: No job too small, short, big, tall or expensive: You can't faze a good estate agent. Whatever your wishes, says Chris Partridge, there is something on the books

THE NEW flat on the top of Fountain House, Park Lane is the London apartment with most superlatives. It is probably the biggest - it occupies the entire block between Park Lane, Mount Street and Aldford Street. It may have the most car parking space - room for 12 limos in the building's basement. To top everything, it is almost certainly the most expensive - pounds 15m for the long lease, and it is not even fitted out yet. Bringing the shell to the standard of luxury the buyer will certainly expect is likely to cost as much as pounds 2m more.

The flat was formed by adding two extra floors (the ninth and tenth) to the 1930s apartments next to Grosvenor House and near the block where the Fayed brothers, owners of Harrods, have a spectacular penthouse. Strolling round the flat gives you a panoramic view of London's skyline: Canary Wharf to the east, Big Ben to the south, Westminster Cathedral to the west and the Telecom Tower to the north. The main rooms look out over Hyde Park.

The site is so spectacular that even when it consisted only of air above the original roof, it was attracting offers of pounds 5m. If the flat is not sold as one, it will be split up into four two- storey maisonettes. Peter Wetherell (071-493 6935), the Mayfair estate agent who is marketing the property jointly with W Ellis & Co, is keen to avoid this. 'The flat is amazing as it is and once split up you could never put it back together again,' he says.

Its size and cost make this penthouse stand out, but the market is loaded with other highly unusual dwellings, offering something very special for those with the individuality and hardihood to live in them. Estate agents love and hate unusual houses. They are difficult to put a value on, difficult to sell, and attract time-wasting tourists posing as buyers. But they also attract immense publicity and - estate agents being romantic souls under the bluff exterior - make a change from the usual s/d, three bed, two receps that are most agents' bread and butter. Here is a guide to some unusual properties most would love to have on their books.

LARGEST AND SMALLEST

Right now, the largest and smallest houses are probably within a few miles of each other. Pierrepont, in Frensham, Surrey, is a half-timbered cottage with elephantiasis. It was built in 1876 by Norman Shaw, who designed a suitable mansion for the owner of a 2,655 acre estate, complete with great hall, library and a study with an inglenook larger than most dining rooms. Since the Second World War (when it was requisitioned for British and Canadian troops) the house has been used as a school, which added classrooms and workshops, but the estate has shrunk to a mere 35 acres. Vendors and planners alike are clearly unable to think of any suitable use for the buildings. The complex is on the market with Knight Frank & Rutley (071-629 8171) at pounds 1.75m.

Possibly the smallest house is a few miles away at Godalming. It is a tiny Georgian pavilion known as The Summerhouse, built in the grounds of one of the grand houses in the town, now converted into offices. The most expansive feature of this Wendy house is the view, which extends right over the town. The actual accommodation consists of a sitting room and bedroom with miniature kitchen and shower room. The garden, however, is a generous quarter of an acre. Hamptons Messenger May (0252 714164) are asking pounds 75,000.

TALLEST AND SHORTEST

Peterson's Tower at Sway, on the edge of the New Forest, is a pencil-thin structure built in the Mogul style in 1885 by a retired India hand with a conviction of the superiority of concrete as a building material. He certainly succeeded in proving its durability, as the exotic carving is still as sharp as ever. The overall effect is somewhat harsh, however, and buyers should be aware that there is no possiblility of inserting a lift. This ripely eccentric house has been immaculately restored over the past 15 years by Paul Atlas, who has run it as a restaurant and hotel. He is seeking offers in the region of 650,000 guineas through Gwyn Headley of Pavilions of Splendour (081-348 1234).

You suffer from vertigo? What about a house with no height at all? Underground houses are popularly assumed to be dark, damp and generally similar to the Count of Monte Cristo's suite in the Chateau d'If, which is probably why enthusiasts for modern underground houses always refer to them as 'earth- sheltered homes'. The technique is to dig a hole, build the house in it, and cover it with all the spoil. The earth shield is an unrivalled insulation layer, and a skylight in every room fills the house with light.

In many beauty spots, underground houses are the only sort with a hope of getting planning permission. Such is the case at Ashmead House, a site near Burford, Oxfordshire which is being offered for sale with planning permission for an earth-sheltered house. Two alternative schemes have been given the go ahead: a modern design round a central swimming pool or a more classical design round a columned courtyard. Cost of the site includes construction of either scheme - pounds 275,000 or pounds 250,000 - although if a buyer wanted something completely different that would be negotiable. The agent is John D Wood (0865 311522).

MOST TRAGIC LEGEND

Scottish castles usually come complete with grisly legend of betrayal and torture. Forter Castle, near Blairgowrie, is said to be the place - immortalised in a ballad as 'The bonny house o' Airly' - attacked by the Duke of Argyle when its laird, Lord Ogilvy of Airlie, was away fighting for Charles I. The Countess surrendered on the promise that the castle would not be damaged, whereupon Argyle led her up the hillside to see the house burn to the ground. She collapsed and died on the spot.

Forter Castle was indeed burnt, in 1640, when rebellion against Charles I broke out in Scotland. The Scottish Committee of Estates declared the Catholic Airlie family 'malignants' and ordered their strongholds demolished. Little more than the walls remained in 1988 when the castle was bought by the present owners, although soot from the fire still covered the interior. The castle, complete with beamed ceilings and nail-studded oak doors, is now a comfortable home with some of the loveliest views in Scotland. It is on the market at pounds 450,000 with Savills (0356 622187).

SMALLEST INHABITED ISLAND

Lihou Island, off Guernsey, is 40 acres of haven (tax haven, that is). It consists mainly of rocks and very small plants - 100 different varieties of grasses, lichens, ferns and wild flowers have been recorded. The swimming pool is known whimsically as Venus's pool because it rises from the waves every time the tide goes out. The house was built in 1978 from the stones of the previous house, which had been used for target practice by German gunners during the war. Lihou is for sale through Knight Frank & Rutley at pounds 850,000.

FASTEST AND SLOWEST SALES

'The fastest transaction I dealt with,' says Edward Waterson of Carter Jonas, 'was in York. A girl came into the office at 10.30 having viewed a property that morning. She said she wanted to be in quickly and asked me how long it would take. I said six to eight weeks was the norm but she said she wanted to be in that evening. We spoke to the bank, who confirmed she had the money, so I rang the solicitors and they prepared a contract which was exchanged that lunchtime and completed by 5pm. It shows how these things can be done if necessary.'

Simon Coan, director of Winkworth's Battersea office, sold a house in the sought-after area between Clapham and Wandsworth Commons before he had finished measuring the place up. 'I knew a person who would be interested, so I took him along when I went to take the measurements and he made an offer there and then,' Coan says. This is certainly one way of keeping marketing costs to a minimum.

Another London firm has a property which has been awaiting completion of the contract for more than two years. The vendors are happy hanging on to the 10 per cent deposit without the need to move, and the purchasers are happy that when they finally want to move they have their dream house lined up and ready.

MOST OVER-THE-TOP PAD

The slump in property prices hit hardest the trendies who moved east to immense and greatly over-priced converted warehouses in London's Docklands. So it is heartwarming to see that the most conspicuous warehouse conversion of all has been put up for sale with a multi-million pound price tag and every prospect of selling eventually. Sun Wharf was converted from a row of four Victorian warehouses on the Thames at Limehouse by Sir David Lean, the film director, who died in 1991. It was his pet retirement project, involving many hours of playing with models to get exactly the right theatrical effects. Two warehouses were completely demolished except for the street-side walls to form a garden. Lean's highly individual creation came on the market a few weeks ago at pounds 3m with Savills.-

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