Samuel Hartlib, the German polymath, wrote that Marshal had by 1650 produced a florilegium for the botanist and gardener John Tradescant the Younger.
His album of 63 folios has 129 watercolours of a variety of insects – butterflies, moths, caterpillars, beetles, locusts, spiders, flies, and crickets – some by other artists.
He enlisted the aid of Tradescant, and of his friend Henry Compton, Bishop of London, in acquiring many rare, exotic insects.
[8] His final years were spent at Fulham Palace, the home of the earls' brother Bishop Compton, from 1675 until his death there on 7 December 1682.
He was buried at All Saints Church, Fulham, in front of the altar, where an inscription on his tombstone reads, in part:[9] He left no issue, but, by reason of his integrity and gifts he will live longer than the life which was vouchsafed him.When Dorothea died in 1711, she bequeathed Marshal's florilegium to her nephew Robert Freind.
[10] A selection of Marshal's works was shown at the "Amazing Rare Things: The Art of Natural History in the Age of Discovery" exhibition at The Queen's Gallery, Buckingham Palace, curated by David Attenborough.