Philip Norton, Baron Norton of Louth, FRSA (born 5 March 1951), is an English author, academic and Conservative peer. He has been described as "the United Kingdom's greatest living expert on Parliament" and "a world authority on constitutional issues". - from Wikipedia
“It's not that that use of prorogation is unusual; it is the fact the length of time that he seeks the period to prorogue Parliament, which is the longest in 90 years. So we are seeing things that are unusual and unprecedented, but that power's within the extant system.”