Warwick was called up to the Army in 1946, commissioned and appointed to a unit serving in West Africa. There his duties involved arresting Kwame Nkrumah, later the first president of Ghana. Demobilised in 1948, he enrolled at Bournemouth College of Arts to train as a teacher in Art. On graduating, he started teaching on a temporary basis at prep schools in southern England while also exhibiting paintings at the Royal Academy summer exhibition in 1953 and 1954.
 
In 1954 he secured a full time post at Brambletye school in Sussex. After four happy years there he moved on to Uppingham in 1958 as head of a one man Art department. He inherited an empty art school, no formal sixth form teaching and a single 45 minute period each week for the junior classes. On the other hand, he had great enthusiasm, a strong determination to succeed, subversive cunning and an almost evangelical passion to discover young talent and nurture it. For the next 21 years he built up his department until it had four teachers and 30-40 'A' level candidates per year. In 1979 he withdrew from day-to-day management of the department and finally retired from Uppingham School in 1988.


Warwick loved Uppingham - the school and the town and its people - and left a substantial physical legacy behind him including many improvements to the school (including the enlargement of the chapel) and his last great work - a Millennium Map of the town of Uppingham which he designed from scratch. This map has since been reproduced and sold widely to the benefit the fabric of the town.

Warwick was always immensely proud and excited by the achievements of his former pupils. One of them, Tom Ryland, summed him up in these words: "Warwick was endlessly kind and cared deeply about his proteges. He was a hugely influential character to all of us involved with him. To some, he was slightly eccentric...his nasal twang was a gift to naughty schoolboys given to mimicry, but this was affectionate and never malicious."