The friends, who hire stables at Lawmarnock Farm, near Johnstone, Renfrewshire, decided to launch a fundraising campaign for the Beatson West of Scotland Cancer Centre after two of their fellow equine enthusiasts were diagnosed with the condition.
The resulting calendar, Kits Off For A Cure, has proved a hit with the public and sales are on course to break £5000.
It was partly inspired by the recent Slow Down For My Horse campaign, which encouraged drivers to take greater care when passing horses on public roads, and saw riders strip off to raise awareness.
“What began as a joke quickly became a reality. We thought we would raise maybe a couple of hundred pounds, and now we’re at around £4300,” said Ashleigh Sommerville, one of those that took part.
“There’s a range of ages taking part - the youngest is 24 and the oldest is 46 - and a variety of occupations. We all got stuck in as it’s such a great cause.”
The calendar was produced over two months, with a professional photographer who uses the livery yard volunteering her services.
Several local businesses also stepped forward to offer sponsorship for the production, as well as covering the costs of establishing a website.
“The experience has brought us all closer together,” added Ashleigh (31), a training instructor from Bridge of Weir.
“Our friends and family have all been very supportive.
“Although the traffic around the farm seemed to go up when we were taking pictures.”
The popularity of charity calendars featuring men and women in varying states of undress is usually credited to Rylstone Women’s Institute, who published their first effort in 1999.
The group’s story was subsequently dramatised in the popular 2004 film Calendar Girls, starring Helen Mirren.
All proceeds from the Lawmarnock calendar will go to the Beatson centre.
“We’re also accepting donations for those that don’t want to purchase a calendar,” said Ashleigh.
“We’ve been blown away by the response we’ve had so far.”
The Beatson West of Scotland Cancer Centre was officially opened in February 2008.
It provides all the radiotherapy, and much of the chemotherapy, for patients with cancer in Scotland’s west coast.
The centre offers services and care to 60 per cent of Scotland’s population – a total of 2.8 million people.
The Beatson Cancer Charity was formed in February 2014 following the merger of Friends of the Beatson and The Beatson Oncology Centre Fund. The resources of these two charities were brought together to create a single charity dedicated to supporting The Beatson West of Scotland Cancer Centre.
For more information on the campaign, or to order a calendar, visit kitsoffforacure.co.uk.