John Bercow’s former private secretary has made a formal bullying complaint against him as members of the watchdog in charge of appointments to the House of Lords decide whether to block the former Speaker’s peerage.

Angus Sinclair, 67, has passed a dossier of allegations claiming that he was bullied by Bercow to an independent bullying and harassment helpline for current and former House of Commons staff.

It is the third formal bullying complaint made against Bercow in recent weeks and follows those made by Lord Lisvane, a former clerk of the House, and Lieutenant-General David Leakey, previously Black Rod, a senior Lords official. It comes as sources close to the House of Lords Appointments Commission revealed it had “serious” concerns about two of the eight