The woodlands of East Anglia continued to be a source of inspiration for Coker into the 1960s following the first group of Epping Forest works he produced in 1959. In Suffolk, Coker frequented Rendlesham Forest and Tunstall Forest: the latter was the subject of Tunstall Forest I and Tunstall Forest, painted in June and July of 1964 respectively. That same year, Coker had an exhibition at Zwemmer Gallery almost exclusively devoted to works of woods and individual trees – Tunstall Forest I was work 21 in the show.

Whilst Tunstall Forest harked back to the Epping Forest works of the 1959 Zwemmer Gallery show with its vertical orientation and accumulated layers of worked impasto paint, Tunstall Forest I illustrated an evolution in Coker’s practice. Looking across a horizontal sweep of the landscape, Tunstall Forest I has a certain lyricism previously unexplored in Coker’s work. Homogenous directional brushwork is suggestive of movement, of rippling grass and swaying boughs. The low viewpoint, almost a worm’s eye view as if the viewer were lying in the undergrowth, persists from Coker’s earliest landscapes but the expansiveness of the vista is near unprecedented. A broad grassy avenue winds into the heart of the picture, leading the viewer between two flanks of a forest. This potent directional pull is a compositional technique inherited from de Staël, often seen in his depictions of harbour jetties, receding so starkly they read as pure geometrical construction, Coker employed this device as early as Lighthouse, Audierne, 1957. In Tunstall Forest I, the grassy approach acts as a conspiratorial invitation, drawing the eye into the shadows cast by the ancient woodland. A wood of two halves, the left section glows in sunlight whilst the right rests in the gloom
of the shadows cast over it by the left elevation, suggesting the raking light of late afternoon. Above, a triangle of clouded sky echoes the receding grassy verge below. Frederick Laws, critic for the Guardian, commented in his review of the 1964 Zwemmer
exhibition that Coker, “allows [trees] to be, dramatic, elegiac, pure pattern or simple botany.” Tunstall Forest I is the embodiment of this observation: expressive expanses and intimate groves both have their place in Coker’s manifold renderings of woodlands.