Although he was to remain at Farnham for the next 39 years Allen was able not only to pursue his private interests but to undertake artistic commissions for the Victoria and Albert and other museums. These tasks took him to France or Italy each year between 1890 and 1909 in order to survey and illustrate historic buildings for publication at home. In 1904 he was elected to the Royal Society of British Artists.
Back in Farnham Allen continued to be an inspirational teacher at the College. One of his pupils, Harold Falkner, recorded that “At the age of about 15 I was one of the first students to come under his influence. My career was changed from a veterinary surgeon to Architecture. Allen transformed our outlook, which thought nothing of our Georgian past and relegated its furniture to the attics, if it was not sawn up. Allen furnished his house with local Chippendale and Sheraton, opening our eyes to a new world.” Falkner would later be commissioned by Allen to design him a family home, Stranger’s Corner, on the Tilford road.
Both Allen and Falkner were friends of another Farnham character, the author and wheelwright George Sturt, who wrote about the everyday lives of the craftsmen and agricultural workers whose jobs would soon disappear as mechanisation took over on the land.
While Sturt, who also wrote under the pseudonym George Bourne, was putting his record into print and Falkner was moving to preserve Farnham’s historic buildings, Allen was working with his paintbrush to capture the surrounding countryside. Thanks to their work, urban and rural landscapes began to be preserved at a time when 'progress and modernisation' appeared to be sweeping all before them.