MERCURIUS POLITICUS, London, England, June 25 to July 2, 1657  An uncommon newsbook (the forerunner of newspapers) with the balance of the title reading "Comprising the sum of  Forein Intelligence, With The Affairs now on Foot in the Three Nations of England, Scotland and Ireland. For Information of the People."
This title was published by the famed Marchamont Needham. Needham had earlier sided with the Royalists & was consequently imprisoned but gained his release upon switching his loyalty to Oliver Cromwell and the Parliamentarians. This newsbook was a platform for the Commonwealth regime.
Great content here as it reports the second investiture [he initially become Lord Protector on Dec. 16, 1653] of Oliver Cromwell as Lord Protector of the Commonwealth. In 1657, when the constitution required his second investiture as Lord Protector, he sat in the coronation chair used since 1308. The ceremony moved to Westminster Abbey, and adopted aspects of the coronation ceremony. 
The very detailed report takes all of pages 5, 6 & 7 and is headed: "An Exact Relation of the Manner of the Solemn Investiture, or Happy Inauguration of his Highness the Lord Protector at Westminster."
This is terrific reading, as it contains all the ceremony of a coronation despite him not being a king. Historians note, however, that Cromwell was a defacto king despite his title inferring leader of the Commonwealth.
It begins: "Friday the 26 of June, 1657 being agreed upon for the investiture of his Highness the Lord Protector...at the upper end of Westminster Hall...". Included as well is Cromwell's oath prefaced with: "...These things being performed, Mr. Speaker...administered the Oath to his Highness, prepared by the Parliament, the form whereof is as follows..." and what followed is the text of the oath. Then more on the ceremony including: "...After this the people giving several great shouts, and the trumpets sounding, his Highness sat down in the Chair of State, holding the scepter in his hand..." and also: "...a Herald stood up aloft, giving a signal to a trumpet to sound three times...there publish and proclaim his Highness Lord Protector of the Commonwealth of England, Scotland, and Ireland, and the Dominions and territories thereunto belonging, requiring all persons to yield him due obedience. Hereupon the trumpets sounded & the people made several great acclamations with loud shouts, 'God save the Lord Protector'..." and more.
A period account (the week of this publication) of the investiture or 'inauguration' of Oliver Cromwell as Lord Protector is not just extremely historic but very rare. This is the first we have seen.
Complete in 16 pages, 5 1/2 by 7 1/2 inches, a bit close-trimmed at the bottom margin affects one line on one page, very nice condition.