Post will once again be delivered by steam trains across Scotland as historic locomotives feature in the latest batch of collector stamps issued by Royal Mail.

The trains, some of which date back to 1897, served the country before the introduction of diesel and electric engines in the 1960s.

Classic Locomotives of Scotland, issued on Thursday, features period photographs of the trains at work.

Philip Parker, Royal Mail stamps spokesman, said: "Scotland has an incredible railway heritage, not just in terms of its locomotive production, but also its iconic structures such as the Forth Bridge, then the world's first major steel structure.

"We hope that the four locomotives featured will remind people that behind the glamour of the passenger locomotives, these 'servants of steam' were busy building a new Scotland."

The first-class stamp features the Glen Falloch and Glen Loy running on the West Highland line at Ardlui in 1959. The locomotives were built in 1913 and 1920 respectively at Cowlairs Works in Glasgow.

The other three stamps in the issue feature the Andrew Bain and Bon Accord locomotives arriving in Aberdeen, and the Clan Mackinnon train passing the Kyle of Lochalsh in 1948.

The earliest railways in Scotland were built for commercial and industrial purposes to transport coal to waterworks, but the networks quickly expanded to forge links with the growing number of factories, quarries and docks.

Royal Mail has issued special stamp collections commemorating events in UK history for almost 50 years and there are an estimated 2.5 million stamp collectors worldwide.

The Queen approves all UK stamp designs before they are printed and issued.