J.L. Carr was basically a self-taught artist although he did take a course in handicrafts while at Dudley Training College. He drew many of the buildings and figures on his maps and designed the covers of many small books. He painted using watercolours, poster paints and acrylic paints on a mixture of media - paper, card and board, sometimes prepared with egg white. He also recovered Weldon stone lintels, a Lincolnshire limestone, from demolished buildings and carved out figures to decorate his back garden and, in three notable instances, to replace figures that were destroyed in his local church in Kettering during the reformation. Carr painted a picture of Wedldon quarry in 1960 (NR32) and wrote beneath it: From this hole was gouged half of Kings College, Cambridge.
Carr had an understanding of church architecture, which he described in the introduction to The Northamptonshire Record:
When I was a pupil at Castleford Secondary School in the 1920s, the Latin master, Patrick Delaney, arranged one or two trips to local buildings – to see the Norman apse at Birkin, and the abbey at Selby and these supplemented a course in church architecture taught by Miss Alice Gostock geared to the School and Higher School Certificate of those days. One of the spin-offs of this was a rough idea of architectural dates and terms so that wherever I happened to be, I looked at buildings.
A painting of a rural schoolhouse - Huron, South Dakota, 1956
On Saturdays in winter (when there was no cricket), mostly between 1960 and 1964, Carr borrowed Arthur Mee's book on Northamptonshire and planned circuits of buildings which Mee claimed to have notable architectural or historic merit. These were usually related to churches or old buildings, even dovecots, but he also painted views across the bleak landscape and then finished them all off in paints at home in the back bedroom on a Sunday morning. Initially he used the same powdered paints that his school-children used in their art classes, which were mixed with water, and then later used tubes of acrylic paint, sometimes applying it straight from the tube with his finger and a tissue when he had forgotten to take brushes with him.
Carr's hand-written, mimeographed list of pictures in what he called The Northamptonshire Record numbers 385 buildings, places or items, but there may be more in the final version, which consists of seven bound volumes of pictures held by the Northamptonshire County Archive.