The illustration is from the Sege of Thebes; it shows Lydgate, arm extended, telling his tale on the return journey from Canterbury to London, described in the Prologue to his Sege of Thebes.
John Lydgate, Chaucer's most prolific admirer, was born in Suffolk in 1370 in the village of Lydgate near the abbey of Bury St. Edmund's, which he entered as a postulate when he was about fifteen years old. He remained a monk the rest of his life, though he travelled outside his cloister (to Paris at least once, in 1426), and his patrons were powerful aristocrats and courtiers. For a good brief biography see the life by Clare Sponslor in the Literary Encyclopedia.
Over 100,000 lines of his verse survive, much of it in enormous works of translation -- The Troy Book (over 30,000 lines) [Widener 11473.97], The Pilgrimage of the Life of Man (24,000 lines) [Widener 11473.77], and The Fall of Princes (26,000 lines) [Widener 11473,121].
These were all written to order, for powerful patrons. Lydgate did better when he was writing for himself, as seems to have been the case in his many short poems [see The Minor Poems Widener 11473.107], and perhaps even The Sege of Thebes, which is a late work. The Secrets of the Old Philosophers, a book of instruction for princes, which was begun by Lydgate and finished by Benedict Burgh, contains a discussion of alchemy (translated into modern English), which is of some interest to one's reading of the Canon's Yeoman's Tale.
The long Fall of Princes, a translation of Laurent de Premierefait's translation and adaptation of Boccaccio's De casibus virorum illustrium is of some interest to a reading of Chaucer's Monk's Tale; see Tragedy of Sampson, translated into modern English.
Lydgate was especially taken with Chaucer's "high style," which he developed into the elaborate "aureate" style that characterizes much of his verse (See The Epithalamion for Gloucester), and that was carried to even greater heights of elaboration by Lydgate's imitators, such as Benedict Burgh. Yet Lydgate does not do too badly when he tries to imitate Chaucer's more colloquial style in his Prologue to The Siege of Thebes.
For Derek Pearsall's bibliography of critical and scholarly works on Lydgate click here.