Windsor's biggest, grandest and most expensive home is for sale. It comes with royal connections, enough bedrooms for an army and an unbeatable location just off Windsor Great Park. But before you get carried away, I am talking about Hadleigh House, not Windsor Castle. Technically, Hadleigh is only Windsor's second-finest house, but if you can't have the castle, it is the next best thing.

The house, built in 1793 by the Mayor of Windsor, has 5,870 sq ft of space and eight bedrooms over five floors. “It's the biggest house in town,” says the agent, who claims that it will be the most expensive house ever sold in Windsor if it achieves its asking price of £3.75 million.

According to a history of the house, written by Angus Macnaghten, a former resident, John O'Reilly, George III's doctor (something of a difficult job), bought the house in 1811. Upon his death it passed to his partner, Henry Brown, doctor to George IV and Queen Victoria. George IV objected to Brown's habit of using the castle driveway, and forced him to move the entrance to Hadleigh House to the rear, on Sheet Street. Today, the original park frontage is still discernable from the back garden.

The current owners, a retired businessman and his wife, bought the house in 1999 and undertook “a huge amount of work. We did it in conjunction with English Heritage and it took 18 months and £600,000.” They added three bathrooms and saved the top floor, which had housed staff and still has a row of bells, from falling down. Other original features include fireplaces, cornices and a visitors' book kept since 1917. The house is just one room deep, so most rooms have windows on both sides that overlook the attractive, medium-sized garden. The decor is old-fashioned but comfortable. The family spend most time in the large kitchen and breakfast room on the lower ground floor. Upstairs are more formal rooms: a dining room linked to the kitchen by a dumb waiter and a drawing room, plus a study and sitting room. The en suite master bedroom has a shower room and dressing room down a tiny staircase, and the seven further bedrooms are on the upper floors. A spacious one-bedroom flat over the three-car garage would be great for housing nannies or grannies.

The only drawback is aircraft noise, which is muted by triple glazing. “You can't get over the fact that you're under the flight path,” the owner says. “That's just Windsor I'm afraid.” He and his wife are looking to downsize as their children have left home. “We'll be sad to go,” he says, “but it's an enormous pile of bricks for just the two of us.”

Savills 01753 834600

Fast facts

The average house price in the Slough area (which includes Windsor) is £400,221. 125 homes sold for over £1m in Windsor last year. Source: Halifax .

More than 50 per cent of local households have managerial or professional jobs; the UK average is 38 per cent.

Times recommends

• Second homes: credit crunch casualty or money-spinner?
• How I built my own sliding house
• Top 10 incentives for house buyers