Picking someone as Britain's worst ever ruler is certainly no easy task. How does one pit someone like the Saxon Ethelred the Unready with say the 20th Century's Edward VIII? In spite of this, a group of high profile historians have got together with English Heritage and come up with a top three failures; a trinity of shame if you will.

The first on the blacklist is Mary I of Scotland. More commonly refered to as Mary Queen of Scots, Mary I was crowned Queen of Scotland and betrothed to the infant son of Henry VIII before she was even nine months old. Coronated on the 9th September, 1543, Mary's reign was fraught with difficulties and bad decisions that ended with a period of crushing incarceration before a grisly execution.

When her second husband, Lord Darnly, died in an explosion, Mary was considered the prime suspect in his murder and seriously began to fall out of favour with members of the Scottish court. She then severely exasperated the controversy by marrying the other chief suspect in the case, the then Earl of Bothwell, just three months after Darnly died.

Forced to abdicate her position, Mary fled to England believing that Elizabeth I would protect her from an uprising of her nobles. Instead, the Queen of England was forced to inquire into the death of Darnly and threw Mary in prison.

For the next 19 years Mary devoted herself to plotting the Queen's downfall. Involved in countless Catholic conspiracies, Mary was executed for Treason in February 1587.

After her death, Mary's reputation blossomed as a symbolic and romantic figure. A Catholic martyr, Mary Queen of Scots has never been officially canonised by the church but the intensity of her suffering at the hands of both Darnly and Bothwell and then Elizabeth, has lead many to sympathise with her plight.

In spite of her more endearing treats (she was a renown beauty and had mastered several languages), if one is to judge the success of her ability to rule then she certainly doesn't come off too well. The historian Sarah Gristwood, for example, described her actions while Queen of Scotland as "irresponsible to the point of criminality." Whatever we may think of her personally, she was undoubtedly a lousy monarch.

The second candidate in the top three is King George IV. Ruling as the Prince Regent whilst his father, King George III, was prone to bouts of madness, and then as King from 1820-1830, George was a serial womaniser and huge squanderer with lavish and gaudy tastes. Frivolous at a time of great social distress, many of his subjects held the King as a fool and a playboy.

Despite seeing Britain's victory over Napoleon's French military, George spent far more time and money on expensive palaces like the opulent Royal Pavilion at Brighton and on his various affairs and strings of mistresses.

A total cad and a bounder, George IV (played to the hilt by Hugh Laurie in Blackadder III) earns his position in the trinity of shame by exhibiting almost complete disregard for his office and his subjects.

The final candidate on the shortlist is Edward II. A terrible soldier, during Edward's reign he managed to lose control of Scotland to Robert the Bruce at Bannockburn in 1314. He also lavished expensive gifts and privileges on his male favourites, especially the French knight Piers Gaveston, a relationship which formed the basis of the king's rumoured homosexuality.

Edward was forced to abdicate under grounds of incompetence and was imprisoned by his wife's family. One thing that is famous about Edward II's demise is, of course, his rather grisly end. Most famously described by the historian Raphael Holinshed in the 16th century, the account of Edward's murder has gone down in history as one of the most gruesome of all time. The whole 'Did they? Didn't they?' was made all the more famous when Christopher Marlowe decided 'that they definitely did' and used Holinshed's description to close his play, called simply: Edward II.

So, there's the shortlist. Not exactly Britain's finest moments, granted, but are they really the worst rulers? What about Edward VIII who completely chickened out? Or what about Richard the Lionheart? Who, despite being born in Oxford (and having a cool name), was quite clearly French, spoke very little English, tried to overthrow his father Henry II and spent almost the entirety of his 10 year reign off in the Middle East murdering Jews and Saracens in a vain quest to capture the holy lands. Nice chap.

I suppose, just as in deciding Britain's best monarch, it all comes down to matters of personal opinion. After all, was Queen Victoria the elegant Empress of India that dutifully resided over a commonwealth on which the sun never set; or, was she a vainglorious tyrant that condoned the disgusting exploitation of the poorest and most vulnerable people on the planet?

It just comes down to perspective doesn't it.