Claymore - I would suggest you read Antonia Fraser's book on Cromwell. Cromwell was a member of a legally assembled parliament. He fought on the parliamentary side in defence of the rights of the people against a King who ardently believed in the "Divine Right of Kings" (to do what ever they wanted, whenever they wanted), a doctrine that challenged the rights won by the barons with the signing of the Magna Carta.

Gareth - "Incidently Cromwell, and his religious fundamentalists, tried to ban football, along with the Maypole, and Xmas. "

Cromwell did not - the Levellers were the fundamentalists you mention and Cromwell did much to water down what they proposed.

The United Kingdom has never experienced a military coup wrt the overthrow of an elected government. We've had lots of instances of rebellions and threats of foreign invasion, but no military coups.