A series of medieval sketches found on the walls of a north Norfolk priory could give an insight into how the village's historic parish church was designed.

From 21st-century teenagers with short attention spans to 13th-century schoolboys whiling away a service – grafitti has been scrawled over the county's churches for hundreds of years.

But a series of medieval sketches found on the walls of a north Norfolk priory could reveal a lot more than the thoughts of a bored parishioner.

Volunteers involved in a community archaeology project in Binham believe their discovery could give an insight into how the village's historic parish church was designed.

The Norfolk Medieval Graffiti Survey is working its way through the county seeking out markings, doodles and messages scrawled on their walls by past parishioners.

So far the volunteers have visited 50 of the 650 stunning medieval churches and uncovered everything from scribbled prayers and names to tracings of hands and caricatures.

Matthew Champion, project director for the NMGS, said: 'Medieval graffiti could be created by anyone. It's a way into understanding the commoners of the parish.'

But now they have found something on a much grander scale. A series of newly-discovered drawings which are thought to be the workings out of a master mason for the historic Priory Church of St Mary and the Holy Cross at Binham – and maybe even its revolutionary west front.

Mr Champion, who lives near Fakenham, said: 'It was difficult to believe what I was seeing at first as it was on such a large scale. Most graffiti inscriptions tend to be relatively small and modest.'

Instead, arcs and lines covering areas of up to 8ft were found etched into a wall which the volunteers believe are the master mason's working drawings of plans for part of Binham Priory.

Looking at a sketch of the markings, Sandy Heslop, professor of visual arts at the University of East Anglia, said they were clearly more than an idle doodle. He said: 'You don't do something on this scale because you're bored at lunchtime. Clearly this was part of a process of working something out – what part of which working something out is what needs serious investigation.

'These kinds of inscribed architectural designs are really, really fascinating.'

Mr Champion, who works as a freelance heritage project manager, said it was clear to him that the lines represented sketches by a mason –something which had been found on a smaller scale in other historic buildings – since point holes from compasses and dividers could still be made out.

But he also believes they could relate to Binham Priory's famous and distinctive west front.

He added: 'There is no other front quite like it. Any architectural historian who saw it would say 'that's Binham'.'

The once-intricately designed west front, whose windows have since been bricked up, is thought to be one of the earliest surviving examples of bar tracery in Britain.

The method, which involved incorporating the shapes of windows into the design of a building rather than cutting them into stones and weakening the structure, went on to transform early Gothic architecture.

The west front is thought to have been built between 1226 and 1244 while the bar tracery of Westminster Abbey dates from 1245.

Prof Heslop, who specialises in medieval art and architecture, said: 'There is general agreement of [the priory's] importance. Bar tracery is one of the great architectural revolutions. It influences how much of the architecture across Europe looks, so anything that helps us understand the early development of bar tracery is very helpful.'

The UEA professor said further detailed study of the markings would be needed to determine exactly what part of Binham Priory they represented.

He added: 'If it is the west front, it is very significant because you can sort of see overall designs and a series of related arcs which make it look as though they are trying something out.

'It's definitely important. There are no two ways about it. A proper study will reveal if and how it relates to the west front and which part of the west front.'

Mr Champion said the NMGS volunteers would continue their survey of the priory and hoped to publish their findings in an academic journal.