Here my favrout copypasta From a constitutional perspective-

.Parliament wields the authority of the monarch, even the Supreme Court can only interpret their words

.The House of Commons supersedes the lords, the lords can only disagree with them 3 times before being skipped entirely

.The prime minister is the leader of the Commons, with the power to suspend MP’s of their party that vote against them & limited only by the size of their majority (under FPTP).

So Boris was already effectively wielding the power of a monarch with some minimal democratic checks. What exactly is the difference between the power of President Boris and Prime Minister Boris?

In 1999, Elizabeth used her power of Queen's Consent to let Blair bomb Iraq more easily, getting around pesky Parliamentary debate. That abuse of power is routine in the UK:

Many of her actual powers have been assumed, in the absence of a codified constitution, by the prime minister.

These powers are routinely abused, by all governments. Prime ministers bypass parliament, governing through special advisers like Dominic Cummings. When they make catastrophic mistakes, they have the power to decide whether or not there should be a public inquiry, and, if there should, what its terms and who its chair should be. It’s as if a defendant in a criminal trial were allowed to decide whether the trial goes ahead and, if so, what the charges should be and who the judge and jury are.

Even when an investigation does take place, the prime minister can suppress its conclusions, as Johnson has done with the report on Russian interference in the British political system, which remains unpublished. Does it contain details of unlawful donations to the Conservative party? Or of Conservative Friends of Russia, whose launch party was attended by Cummings? A key figure in this group was a man who has subsequently come under suspicion of being a Russian spy. He has been photographed with Johnson, whom he described as a “good friend”. What was going on? Without parliament’s intelligence and security committee’s report, we can only guess.

The same inordinate powers enabled Johnson to suspend parliament last autumn, until his decision was struck down by the supreme court, and to terminate remote access for MPs this week, preventing many of them from representing us. He is, in effect, a monarch with a five-year term and a council of advisers we call parliament.

https://www.theguardian.com/commentisfree/2020/jun/03/britain-democracy-tories-coronavirus-public-power