In 1583 Walmsley made before the Court of Common Pleas an attempt to sustain the validity of papal dispensations and other faculties issued during the reign of Mary I.
Walmsley early showed his independence by allowing bail in a murder case, contrary to the express injunctions of the Queen conveyed through the lord chancellor; his temerity provoked a reprimand.
He was also a member of the special commission before which Robert Devereux, 2nd Earl of Essex was arraigned at York House on 5 June 1600, and assisted the peers on his trial in Westminster Hall, 19–25 February 1601.
In Calvin's case Walmsley again showed independence: the matter was discussed by a committee of the House of Lords, with the help of the common-law bench, Francis Bacon, and other eminent counsel, in the painted chamber on 23 February 1607, and on the following day was decided in the affirmative by ten out of the twelve judges.
He adhered to his opinion on the subsequent argument in the exchequer chamber (Hilary term, 1608), and induced Sir Thomas Foster to concur in it.
His monument, which was copied from that of Anne Seymour, Duchess of Somerset in St. Nicholas's Chapel, Westminster Abbey, was demolished by the insurgents at the outbreak of the First English Civil War.