Abbot number 15: Henry Monyash
In another long reign, Abbot Henry ruled for 39 years and 11 weeks, from 1400 to 1439. Something of his career history is known: in 1379 he was ordained subdeacon, in 1381 he was ordained deacon, and in 1383 he was ordained priest.

An endowment was made in this reign by William la Zouche of Harringworth. St Mary’s Abbey had been given the right to appoint vicars of Ilkeston during Abbot William de Boney’s rule. Some time during Abbot Henry's rule, the Pope appointed a John Aston to this post, whereupon the abbot appealed to the crown. Aston was imprisoned, but as he was unable to bail himself out, the king ordered him freed, on the 20th February 1398. He promptly returned to Ilkeston. The Bishop of Lichfield wrote to the king on the 27th June 1400 to get action and appears to have succeeded.