At Madrid he edited the New Testament in Spanish, and translated the Gospel of Saint Luke into the language of the Zincali.
Leaving the service of the Bible Society he returned to England in 1839, and shortly afterwards married a Suffolk lady.

In 1841 he published _The Zincali_, or an account of the Gypsies of Spain, with a vocabulary of their language, which he proved to be closely connected with the Sanskrit.

This work obtained almost immediately a European celebrity, and was the cause of many learned works being published on the continent on the subject of the Gypsies.

In 1842 he gave to the world _The Bible in Spain_, or an account of an attempt to circulate the Gospel in the peninsula, a work which received a warm and eloquent eulogium from Sir Robert Peel in the House of Commons.

In 1844 he was wandering amongst the Gypsies of Hungary, Walachia, and Turkey, gathering up the words of their respective dialects of the Romany, and making a collection of their songs.