Who was she, this formidable but glamorous WAAF with the big hazel eyes and the high cheekbones? Was she called Margaret, or was Roan a misspelling of Rowan? Did she pose, both so formal and so sensual, one quiet afternoon when no Spitfires were being scrambled? Or was she the fond fantasy of some artistic pilot?

We will almost certainly never know. The WAAF in question is one of three vivid women's faces painted on the wall of the officer's mess at Castletown airfield, near Thurso, during the Second World War.

For 70 years, long after the young men and women of No13 Group Fighter Command who protected Scapa Flow have grown old and memories have faded, the WAAFs have endured.

The paintings are part of a remarkable survey of wartime graffiti collected by the Royal Commission on the Ancient and Historical Monuments of Scotland (RCAHMS) and revealed as part of its centenary celebrations this year. Experts from the commission recorded the WAAF images on the walls of a church at Castletown, which during the war was used by officers. In recent years it became a garage.

“The paintings are sadly under great threat, because the church they are in is leaking and the plaster is crumbling,” said Dave Easton, who has toured Scotland recording the historic graffiti. “The artwork is done with domestic oil paint and it looks like the painter was a trained artist. The detail is wonderful. We find this a lot — that there are only fragments left. Our job is to record them before they disappear for ever.”

RAF Castletown opened as a satellite of Coastal Command at Wick in 1940 and became a fully independent fighter station. The airfield's tasks were flying coastal patrols and providing fighter cover for Scapa Flow and the arctic convoys. The last squadron, No504, left Castletown in April 1944 and the station closed in mid-1945.

“As the war went on they needed more and more personnel to service the equipment, such as the gas contamination centre, and the WAAFS were brought in to run things. The men were kept well away from the females,” said Mr Easton.

The treasure trove of quirky memorabilia recording the human side of the Second World War in Scotland is accessible to the public, online or in person at the RCAHMS headquarters in Edinburgh. Other, more romanticised drawings of women dating from the 1940s — including Dinah, the fantasy showgirl — were found on the walls of the derelict ammunition factory at Dalbeattie, in the remote Galloway hills, where nitrogyclerine was made during the war.

“The walls are covered in poems, drawings, naked ladies and calculations — lots of maths. I think the shift workers were trying to work out how many units they had produced so they would get paid correctly,” Mr Easton said.

Spectacular artwork was also recorded at Donibristle airfield, overlooking the Forth in Fife, which was used as a Royal Naval aircraft repair yard in the Second World War. Here was found a humorous frieze on the wall of the officers' mess in which all the people in the fleet air arm were depicted as Egyptians doing their jobs.

Another surviving example of wartime art was discovered in the old Grant's shoe factory in Arbroath, where Polish soldiers were stationed during the war. The factory had become a nightclub in the 1970s; when the building was stripped out in recent times workmen found a whole wall covered in a Bayeaux-like painting of Krakow, done by the soldiers.

Amongst its extensive photographic archive, RCAHMS has other Second World War treasures such as as the Luftwaffe's entire aerial library of Scottish targets, which shows clearly that Hitler's intelligence at the start of the war was far ahead of that of the British.

The commission hopes to open up the wealth of its collection to the public during its centenary year.

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