In the mid-1930s Rita Angus was in her 20s and working as a freelance commercial artist, writing and illustrating stories in the Press Junior supplement, from a small studio in Christchurch's Chancery Lane.

She was part of a network of independent women working in the arts, including Olivia Spencer Bower, Louise Henderson, cellist Valmai Moffett, and her friend Jean Stevenson, editor of the Press Junior.

[1]: 74–75 In May 1936 Angus took the three-hour train journey to the Mountain Biological Station operated by Canterbury University College at Cass, 116 km (72 mi) from Christchurch.

She also wrote about the landscape: "…those days of clear blue skies, sun setting behind the dark hills, cold shadows, thin smoke from the chimney, ascending in a straight line.

They were happy days…"[1]: 77 Louise Henderson exhibited five Cass-related works based on her sketches at the December 1936 show of The Group, only one of which (the oil painting Plain and Hills) survives, in the collection of the Christchurch Art Gallery.

[2][4] Like the rest of her and Louise Henderson's Cass paintings, this work emphasises the human intrusion into the high country landscapes: huts, trains, radiata pine trees, and telegraph poles.

Angus later wrote that "Cass at that time appeared as a 'break away' from the academic, but resulted from an intense interest in the old masters, through mathematics, e.g. geometry,"[5] and the geometric composition of the painting is strong, with vertical telegraph pole and doors contrasting with the diagonal lines of mountains, roof and shadows.

[7] The central pyramidal form created by the station and trees is echoed and enlarged by the mountains in the background, with shades of purple; the sky is filled with swirling clouds.

[2] In a 1937 Christchurch Press review, the writer suggested Angus had been influenced by Guy Kortright's landscapes,[8] but Christopher Perkins and Rata Lovell-Smith have stronger affinities with her work.

Lilburn borrowed it in 1944, and for years it hung above the piano in his Cambridge Terrace flat, where it in his words "lent warmth and vitality to the room and gave encouragement to my work".

[1]: 185  Lilburn tried repeatedly to buy it, but Angus refused: "No Gordon dear, there is no chance of your possessing 'Cass', ever.…It's useless, I shall not sell.…You will be able to purchase colour prints of some of my work one day, including 'Cass'.

"[1]: 185 Angus once mentioned to her friend Bruce Godward that the New Zealand Railways centenary would fall on 1965, and she wanted to put forward Cass as a design for a commemorative stamp.

The sale was facilitated by her friend Bill Sutton, who was on the gallery's advisory committee, and in whose house Cass was hanging at the time.

The runners-up were works by Colin McCahon, Bill Hammond, Grahame Sydney, Robin White, and Petrus Van der Velden.

In Eldredge's discussion of Rita Angus he places Cass alongside the work of American painter Grant Wood, noting "the telling juxtaposition of present-day subjects and activities with the land’s traditions (alpine or agrarian) bespeaks a similar celebration of time and history.

[24] The station depicted in Cass is a simple two-room building constructed in 1911 with weatherboard sides and a corrugated iron roof.

[31] The painting was displayed cropped at 4k resolution on 64" TV accompanied by a composition from jazz musician Quentin Angus, great nephew of Rita Angus.The NFT in the edition reserved for auction was sold by the International Art Centre on 17 March 2022 for $13,085.