Today, the House of Commons chose Sir Lindsay Hoyle as their Speaker following John Bercow’s resignation. As is customary, Sir Lindsay’s election had to be confirmed by the Queen before he could formally take the Chair. Like prorogation and royal assent, this is handled by Lords Commissioners authorized by Her Majesty’s Letters Patent. But today’s royal commission was a bit unusual in that Lord Chancellor Robert Buckland played the key role.
Historically, the Lord Chancellor presided over royal commissions until 2007 when Jack Straw became the first Lord Chancellor to sit in the Commons since the 16th century. After that, the Lord Chancellor disappeared from most royal commissions. This is because royal commissions are most commonly used for proroguing Parliament, and Lords Standing Order 76 states that
If Her Majesty is not personally present to prorogue Parliament at the close of a session, such prorogation is not to be by Writ, but by Commission directed unto some of the Lords of the Upper House…
Straw appears to have been unhappy with this state of affairs, and he tried to get the Lords’ Procedure Committee to amend the Standing Orders, arguing that “[t]he choice of Commissioners is for Her Majesty; it is not appropriate for the House to seek to limit Her choice by Standing Order.” The committee, however, was unmoved, and the Standing Orders weren’t changed. Since 2007, the Leader of the House of Lords has presided over the prorogation ceremony instead of the Lord Chancellor (though the Lord Chancellor continues to be named as a commissioner, pro forma).
But, as eagle-eyed readers will notice, the Standing Orders only refer to prorogation, and there was nothing to stop Straw from presiding over royal commissions held for other purposes. When John Bercow received royal approbation following his initial election as Speaker of the Commons in 2009, Straw was there in his robes and tricorn hat acting as principal commissioner.
However, the Lord Chancellor did not take part in the royal commissions that approved Bercow’s re-election in 2010, 2015, and 2017. While there has been no official explanation for Robert Buckland’s appearance at tonight’s ceremony, it looks as if a new tradition has been established. The Lord Chancellor presides over the royal commission when a brand-new Speaker is elected, but the Leader of the House of Lords take the reins when the Speaker is re-elected in subsequent Parliaments.
 Following the passage of the Constitutional Reform Act 2005, the Lord Chancellor was no longer ex-officio Speaker of the House of Lords.
 When Straw wrote to the Committee, what is now Standing Order 76 was Standing Order 77.
 The Archbishop of Canterbury is also a member of every royal commission even though they don’t actually take part.
 Had Labour won the 2010 General Election, it’s possible Straw might have been able to preside over two royal commissions in quick succession–one on the first day of a new Parliament to announce that the Queen will declare her reasons for calling the Parliament at a later date and commanding the Commons to choose a Speaker, and another the following day to confirm the Commons’ choice.