Source Currency: Twenty-fifth edition, published May 2019 and updated April 2020, July 2021, June 2022 and November 2023. Erskine May is the eponymous guide to parliamentary practice and procedure, providing accurate and detailed information on the constituent parts of Parliament, its powers and jurisdictions, membership of either House, financial procedure and the process of debate. The fourth update to the 25th edition covers the period up to September 2023 and was published in November 2023.

The main changes in this update include: Changes to the arrangements for appointing temporary Deputy Speakers in the absence of the Speaker or Chairman of Ways and Means (4.32) Removal of reference to House of Lords EU Committee (4.51 & throughout) Changes to process and clarifications relating to the revised Code of Conduct and Guide to Rules; Parliamentary Commissioner for Standards, Independent Expert Panel and ICGS; process in the Committee on Standards; and rules relating to lobbying. Clarification re complaints process (5.2ff & 13.35) Clarification on House of Lords code of conduct (5.41 & 11.37) Replacing R&R Sponsor Body (6.49) Message from King - references to Queen changed to King within amended sections (9.2) Opposition Day used to allocate time for business (18.13) Change of from Regulatory Reform Committee to Business and Trade committee (18.28) Timing of Select Committee statements and statements on Fridays (19.2 & 19.21) Clarification re fate of motions when business interrupted or postponed (20.18) Chair may decline to put previous question (20.25) Publication of Legislative Consent Motions and deletion of EVEL Standing Orders (27.6, 27.7 ff) Various examples and clarifications relating to Questions on Programme Motions, Instructions on Bills, moving of Amendments in Committee and amendments to recommitted bills (28.59 ff) Changes to the EU scrutiny regime and scrutiny of Delegated Legislation related to EU withdrawal (32.1 ff) Clarification on virtual and hybrid proceedings (38.28) Clarification re officers and members attending committees in the other House (38.34) Clarification re EU statutory instruments committee (38.71) Removes reference to HoL EU Committee (40.10) Debates on House of Lords select committee reports (40.42) Change to Procedure and Privileges Committee (HoL) (40.60) Re-referral of Private Bill to Examiners (43.8)