Kirkus left the world of mountaineering two tremendous legacies: firstly his pioneering climbs in Wales and elsewhere, and secondly one of the finest instruction books ever written: Let's Go Climbing!.
Kirkus' series of new routes on "Cloggy" was unparalleled until the emergence of Joe Brown, 20 years later.
Kirkus made a pioneering Alpine-style ascent in the Himalaya, in 1933.
Kirkus was killed in the Second World War, in 1942.
- Kirkus, Colin. Let's Go Climbing!. ISBN 1-904466-17-6.
- Dean, Steve. Hands of a Climber. ISBN 0-948153-21-0.
- Thomson, I.D.S. The Black Cloud. ISBN 0-948153-20-2.