William was the eldest son of Quakers Job and Margaret Allen, who built up a prosperous silk manufacturing business in Spitalfields in London. He showed an early aptitude for science, and was especially interested in astronomy and chemistry.
In 1792 he joined the Plough Court pharmacy, run by Quaker Joseph Bevan. Pharmacies in those days did more than dispense and advise: they also researched and developed new medicines. A good pharmacy like Plough Court, known for its ethical standards and the quality of its products, was an excellent place for an aspiring scientist to be.
In 1794 when Bevan retired, William became a partner. The business thrived and he became wealthy. In 1824 Cornelius and Daniel Hanbury became partners, and the firm became Allen and Hanbury’s. It kept this name until 1958, when it was taken over by Glaxo.
In 1796, Allen founded the short-lived Askesian Society, a debating club for scientific thinkers, who also had the use of the laboratory at Plough Court. It was here that Luke Howard first presented his seminal 1802 paper, ‘On the Modification of Clouds.’
Allen became a Fellow of the Royal Society in 1807, for his work on carbon. That same year, the Askesian Society disbanded. Allen remained active in scientific matters all his life, and along with Jacob Bell, founded the Pharmaceutical Society in 1841, to provide structure to what had previously been an unregulated industry.
He was married and widowed three times. In 1796 he married Mary Hamilton, but she died soon after giving birth to their daughter Mary. In 1806 he married Charlotte Hanbury, who died in 1816. He married Grizell Birkbeck in 1827, but she died in 1835.
William was active in many social and philanthropic concerns. He joined the committee of the society to abolish the slave trade in 1805, having already been an active campaigner. When the slave trade was abolished in 1807, he worked on eliminating slave-ownership itself. When this was outlawed in 1833, he turned his attention to helping former slaves, working with Joseph Sturge on ameliorating the conditions in the West Indies. He helped found the Sierra Leone Company, intended to enable former slaves to resettle in Africa. He and Joseph helped found the British and Foreign Anti-Slavery Society, set up to work for worldwide abolition, and organised its first international conference in London in 1840.
He gave considerable support to Quaker Joseph Lancaster’s ‘monitorial’ system of education. This was an attempt to provide mass education in basic skills at a time when educational opportunities were extremely limited. In 1808 William and others set up the British and Foreign School Society, to promote the Lancastrian model around the world. In 1824 he set up a Quaker boarding school for girls, in Newington, and taught science there himself. He commissioned the first school bus, to take the girls to Sunday Meeting.
Relief of poverty was a lifelong concern. The silk workers in Spitalfields fell on hard times in the early 1800’s, and he organised a soup kitchen. He could always be counted on to subscribe to appeals, and was an active promoter of relief work in Ireland and Greece. He brought a systematic approach to it, designing questionnaires to identify the real needs.
He had enormous faith in the capacities of the poor to better themselves, given the opportunity. In 1813 he became a partner in Robert Owen’s New Lanark community village, with its good living and working conditions, and could see its benefits. In 1823 he set up a self-sufficient agricultural community in Lindfield, Sussex, drawing on extensive agricultural experiments of his own. Labourers were given cottages and plots of land, access to loans, and technical guidance, and did very well. He wrote extensively about the idea of ‘colonies at home’, exemplified by Lindfield. His thinking was that people should not need to emigrate to find a better life, since good opportunities could be created in Britain.
He travelled extensively in Europe and Russia, often with Stephen Grellet, and once with Elizabeth Fry. His travelling was always purposeful - fact-finding, researching a new initiative or need, and/or supporting Quakers and others of like mind.
Allen's Russian connection began in 1814, when he met Tsar Alexander 1, during his visit to London. The Tsar became very interested in the Lancastrian method, agricultural techniques, and Quaker ideas. Daniel Wheeler later spent fifteen years transforming the St Petersburg marshes into good farming land as a result of this visit. In 1819 the Tsar invited William and Stephen to St Petersburg, and asked them to be open with him about what they saw. One significant consequence was after they visited the Tsar's new Lancastrian school. William was delighted with the learning, but appalled by the reading material. He quickly assembled an alternative, through cutting up several Bibles and making a selection of interesting stories. The Tsar was delighted, had it translated into Russian and ensured it was used all over his Empire.
William died in September 1843, and was buried at Stoke Newington burial ground.