Consistency is an over-rated attribute for any poet.

Repetition can lead to a dull reputation for reliability. Continuity in work that is consistently flexible is a different matter. Stewart Conn's work, in drama and poetry over five decades, is evidence of that. This substantial retrospective draws on Stolen Light: Selected Poems (1999) and several other publications from Bloodaxe and Mariscat Press. There are also new poems welcoming his granddaughter Ellis, which appeared in the Scottish Review Of Books last year.

Conn was born in Glasgow in 1936 and reared in Ayrshire; he was head of drama for BBC Scotland (1977-92) and Edinburgh's first Makar (2002-05). He is a poet of moments and movements. The Ayrshire years are often voiced by Todd, a Caledonian cousin of Patrick Kavanagh's disgruntled Maguire and RS Thomas's perceptive Iago Prytherch: "Did he not notice/his shadow diminishing against/the wall?" There is frozen clarity, a fragile force of nature revealing the acceptable, concealing the menacing: "Gazing straight ahead/not at my feet. Giving/no sign of knowing/ how deep the water, how thin the ice."

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Shifts in perception and alteration in focus begin to appear in the later work. Art rescues the introspective air and the picture on the wall gains subjective substance on the page. The wonderful poems in The Luncheon Of The Boating Party (1992) remain personal favourites. Their contained moments of empathy with Renoir are remarkable. The unknown man in the background observes that he "Might have been/from another planet. Mind you/It was a wonderful afternoon." Launching this collection, Conn chose to read the remarkable Renoir In Orkney from the same volume. It is an imaginative leap into the luminous of both place and painter. Over the years, I have found elements in the poem sequence that enhance encounters with the art itself in a gallery.

Variation is also the trademark of Harry Clifton's poetry. Born in Dublin in 1952, like this writer he was schooled at Blackrock College but educated by literature and travel. He has travelled across Africa and the United States, and now lives in Ireland. He held the prestigious post of professor of poetry in Ireland from 2010-13.

At first glance I feared a dreadful error in the title. Covering 30 years, it stops in 2004 - no appearance of either the innovative The Winter Sleep Of Captain Lemass (2012) or indeed the extraordinary Portobello Sonnets, which appeared in Poetry Ireland Review last year.

But they can wait, for this comprehensive Selected Poems does contain Secular Eden: Paris Notebooks 1974-2004, previously unpublished in Europe. These poems offer a migrant's perspective on the immediate and the imaginative. "When I was angry, I went to the river-/New water on old stones, the patience of pools. /Let the will find its own pace/said a voice inside me/ I was learning to believe, /and the rest will take care of itself." Centred in the urban, here is "A self-sufficiency/Feeding, not on roots, /But the dreams of roots." Birdsong in Berlin, sometimes shrill. A parrot call from the past. Melancholic melody.

Paradoxically, since I first published him in Dublin in 1968, the work of Thomas A Clark is the least familiar to me of these three writers. Though I am a long-time admirer of his Moschatel Press (with Laurie Clark), his own work had eluded me. Born in Greenock in 1944, he has now returned to Scotland, having spent much of his adult life in Gloucestershire.

It is with great pleasure I read and welcomed the brief but multiple encounters that make up Yellow & Blue. Images proliferate in short bursts of three- to ten-line episodes. They are nature's palette articulated by gracenotes in emphasis, palimpsests of seasonal colour. The overall intent and effect is beautifully caught in one specific composite embrace of nature and colour: it is "as if all momentum/came to resolution/hills run to the sea/green sits beside blue/today it might be true/in a light that holds it/ steady for inspection".

Stewart Conn is at Aye Write! on April 5