Oliver Cromwell was as adept at killing monarchs as Liz Truss, and after executing Charles I Cromwell hummed and hawed about whether or not to accept the British crowns. In the end he gave himself the modest title of 'Lord Protector of the Commonwealth of England'. Cromwell incorporated Scotland into his commonwealth, he had to occupy the country because a political union between the nations was not possible at this point, a Presbyterian country with a monarchy could not be expected to voluntarily enter into a union with a Republic - this is the only time in British or Irish history this would ever prove to be an issue
https://open.spotify.com/episode/3b3CS8exu05OUSxsqXxlv5?si=9331887aa6c44ef8