he knew the history, but was unable to say why they restored the monarchy after having abolished it. Other than people thinking it was "better" under the monarchy than in their fledgling democracy. So they voted for a dictator/authoritarian/king to return.

It's interesting that someone employed at the Tower wouldn't know basic English history.

The monarchy was restored in 1660 when Charles II was invited back to England by Parliament, in great part due to political instability and factionalism (Puritans v. Monarchists v. Presbyterians, etc.). Oliver Cromwell might have been able to transition the government or at least rule it into a better condition at some point, but when he died, his son did not have the same gravitas. But the key thing is that Parliament did not invite Charles II back as a dictator, i.e. the monarchy was not an absolute one. His restoration was framed as a return to traditional governance rather than a return to absolutism, making it more palatable to the population and Parliament. He had to operate within a constitutional framework influenced by the lessons learned during the Civil War, Parliament retaining some control, which in turn led to the Glorious Revolution when a Catholic (James) got hold of the throne after Charles II died and he tried to institute Catholicism again in England. Parliament (and the people themselves) were not having any of that.

Pete