William Grindecobbe motivated at least in part to rebel as a result of the pressures of papal taxation. Along with Wat Tyler and John Wrawe, he was one of the key leaders of the peasants during the revolt of 1381, leading the townspeople of St Alban's on 15 June. He was executed in 1381 along with John Wrawe and John Ball. His trial and execution was overseen by Henry le Despenser. During the Peasants' Revolt of 1381, he became well known for his actions against the high lord Thomas de la Mare, Abbot of St. Albans. He led a deputation to King
Peasants' Revolt encountered Lady Joan, the King's mother, who was travelling back to the capital to avoid being caught up in the revolt; she was mocked but otherwise left unharmed. The Kentish rebels reached Blackheath, just south-east of the capital, on 12 June. Word of the revolt reached the King at Windsor Castle on the night of 10 June. He travelled by boat down the River Thames to London the next day, taking up residence in the powerful fortress of the Tower of London for safety, where he was joined by his mother, Archbishop Sudbury, the Lord High Treasurer Sir Robert Hales,