In 1821 Dunn died, and, led by a persistent "call," Yeardley decided to settle at Pyrmont in Germany, where a small body of Friends existed.
In 1824 he accompanied Martha Savory, an English Quaker, on a gospel journey up the Rhine from Elberfeld to Württemberg, Tübingen, and other German towns, through Switzerland to Congénies in Central France, where some Friends were and (as of 1897) still are settled.
Upon reaching England they were married at Gracechurch Street meeting on 13 December 1826, resuming soon after their missionary labours in Pyrmont, Friesland, and Switzerland, and visiting asylums, reformatories, and Moravian schools.
After some work in Constantinople, and while waiting for his equipment and tents to proceed to the interior of Asia Minor, Yeardley was smitten with paralysis at Isnik, and was compelled to return to England, where he died on 11 August 1858.
As a preacher Yeardley's racy humour, with occasional lapses into his broad native Barnsley dialect, added to his uncompromising directness, did him good service.