For years, Sarah Piper had to bulk-buy Christmas trees. With four holiday lets on the go, by early December the Cornish farmer’s wife turned property developer would be flat out, draping holly over four fireplaces, carting in four loads of logs and baking four batches of welcoming mince pies. “I had help,” she says, “but it was hard work, especially on top of Christmas itself.”

This year, she is taking it easy. Her rental properties, which include a recently built fifth cottage, are on perma­nent or long-term let; or, in the case of a two-bedroom annexe to her own house, kept for family use. After more than 15 years in the holiday-lettings business, she has called it a day. “The market is saturated,” says Piper, 59, who lives with her husband, John, also 59, at Tregustick farm, in Withiel, near Bodmin Moor. “I get a better return on my money with long-term lets.”

Piper believes the problem has been caused largely by second-home owners who rent out their houses when not using them themselves. “Peak season used to be July and August,” she says. “Now even July is not reliable.”

It’s not just second-homers who are spoiling what was once a profitable sideline for so many. The rich — and indulgent — amateur must shoulder some of the blame. Those owners who thought it would be fun to do a bit of holiday letting, where the income was useful, but not essential. “People who sold their businesses or got big redundancy packages in the southeast bought large properties with outbuildings,” says Nicola Oddy, who covers Cornwall — an especially saturated area — for the buying agency Stacks. “It didn’t need to make a huge amount of money to be a success.”

Even the building work was an enjoyable challenge for people uprooted from jobs, friends and family. In the winter gloom, here was something creative to do. Soon, these new holiday-letters were setting impossibly high standards: under­floor heating, granite worktops, walk-in showers and wet rooms became the norm. Holidaymakers who used to be happy with a woodburner and a bathroom (no shower) learnt to ­expect more. Lots more.

Now, though, a growing number of owners can’t, or won’t, provide what visitors want. Even wealthy incomers are wondering if it’s all worth it. Londoners Liz and Graham Jones, both 48, retired to Cornwall in 2001 after Graham sold his marketing company. They moved to Wenn Manor, in the village of St Wenn, with their children, Charles, 21, Brittany, 18, and Martha, 11. The seven-bedroom pile had a four-bedroom coach house, which they planned to tart up and let out.

“The manor was sold to us as the perfect opportunity: we could live here and help to fund the purchase by renting out the coach house,” Liz says. “But what people expect now in high-end holiday lets is phenomenal. We realised that, what with all the facilities we needed to offer, and commission [paid to a managing agent], you end up making no money.

“We’d have to upgrade the furniture and fittings. Then there’s laundry bills, maintaining the garden and installing broadband. And they can’t guarantee how many weeks they can let it for.”

Instead, the Joneses, like the Pipers, chose to go for long-term lets. “You get none of the bills and a guaranteed six months’ rent at a time, with very little pressure,” Liz says. Now their two older children have left home, and they have invested in a deli and restaurant in the nearby town of Mawgan Porth, the couple are moving.

If they can’t sell quickly, they will rent out the manor and the coach house on long lets. The property is for sale for £1.75m with Chesterton Humberts (01872 278288, chestertonhumberts.co.uk); rental prices start at £3,500 a month for the manor and £995 for the coach house, through Myplaceincornwall.co.uk.

In Devon, Sarah and Michael Stone are selling up to be nearer family after 25 years of doing B&B and holiday lets at the Cider House, a lovely five-bedroom home with two three-bedroom cottages in 16 acres within the grounds of Buckland Abbey, near Tavistock. It’s priced at £2m, with Savills (01392 455700, savills.co.uk).

The Stones have loyal guests who return to one of their cottages each summer (the other is on a long let), but have noticed a lull in recent years. “It’s difficult out of season nowadays,” Sarah says. “In April, May and June, people book at the last minute and look for a bargain.” She, too, blames second-homers. “There are a lot of holiday homes here now, which people let out through agencies.”

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