A few years ago, as one does, I found myself hosting a press conference in Germany for the pop band a-ha, to announce their new tour and album. At the time of the press conference, the album hadn’t been finished, so I was sent a demo version of the album – the raw songs sung with acoustic guitar before they were given the full band treatment in the studio. Several months later, when the album came out, it was fascinating to see how these original songs had been translated into the finished product.

It’s a similar process that occurs across the arts. For writing, you swap demos for drafts, that raw soup of words from which you hope a story might emerge. And for art, drafts become draughtsmanship – drawings and sketches on which the final artwork is based. For all the skill in painting or sculpting, there is something magical in how a true artist can capture a picture in a few lines. That was evident in the Augustus John exhibition at Salisbury Museum earlier in the year – for all the power in the paintings, it was often the simplicity of the original line drawings that moved you more.

Last week, I returned to Salisbury Museum to catch up with their Autumn exhibition: a showcase of the shortlist for this year’s Trinity Buoy Wharf Drawing Prize. It’s a prize that began back in 1994 as the Rexel Derwent Open Drawing Exhibition, and before its current sponsorship was for many years known as the Jerwood Drawing Prize. This year’s competition saw 1,798 entries by 925 entries, with the judges whittling these down to 68 pieces by 62 artists for the shortlist.

It’s a different sort of exhibition to many that the museum holds – rather than being carefully shaped by the guiding hand of a curator, this is more a varied collection of different pieces. The overall theme that does come out, if one can call it that, is a discussion of precisely what drawing constitutes. Its definition feels something of a moveable feast, somewhere on a sliding scale between a purist’s view of something involving pencil and paper, and the looser description of something involving making a mark.

There’s plenty of dexterity on display here with charcoal, chalk and pencil: more envelope-pushing entries involved collages, oil, weaving and embroidery. Rather than that age-old question, ‘but is it art?’, here there were occasions where I found myself thinking ‘but is this drawing?’ Certainly, I appreciated the straighter approaches more, where the artists’ instinct and imagination shone through. Jeanette Barnes’ Study for Cable Cars, one of my favourites, was all energy and movement. Like all great works of art, it drew the eye.