The unexpected powers of Queen Elizabeth II

The role of the British head of state is largely symbolic, but she does have some unexpected powers.

And while many of the stranger privileges enjoyed by the monarch are tied to archaic traditions, others give Britain's longest-reigning monarch considerable powers.

These are some of the Queen's most unexpected powers.

She owns all swans in the River Thames

Well, almost. All unmarked mute swans on the river Thames are assumed to belong to the Queen. She has the power to grant rights over those swans to her subjects.

This is thanks to the historical value of swans. Back in the Middle Ages, nobles traded swans between each other, marking their own birds with distinctive nicks on their bill.

Any without a nick were considered property of the monarchy as opposed to a free dinner for any commoners who happened across them.

These days, the Queen and two historic companies - a London Dyers Guild and the twelfth-century Company of Vintners - take part in an annual 'swan upping' ceremony.

The swan uppers row up the river, catching and marking swans. Any marking is typically a ring around the leg for the purposes of tracking and research.

In the UK, it is an offence to intentionally injure, kill or take a wild native bird, swans included.

She also owns all the whales, dolphins and porpoises in British waters

Any 'fishes royal' washed up or captured within 5km of the shore may be claimed by the Crown.

In England and Wales, any porpoise, dolphin or whale caught or washed ashore immediately belongs to the monarch.

In Scotland, whales too big to be pulled by a 'wain [wagon] pulled by six oxen' belong to Her Majesty.

For those without a wagon and half a dozen oxen handy, that's now interpreted as whales longer than 7.6 metres.

She can drive without a licence and cross borders without a passport

According to the Queen's official website, "As a British passport is issued in the name of Her Majesty, it is unnecessary for The Queen to possess one. All other members of the Royal Family, including The Duke of Edinburgh and The Prince of Wales, have passports."

The Queen is the only person in the United Kingdom who doesn't legally require either a licence or number plates to drive a car on public roads. Like passports, licences are issued in the Queen's name.

She gets loads of birthdays

In New Zealand, the Queen's birthday is celebrated on the first Monday of June.

Australian states set their own dates for celebrating the monarch's birthday.

In most states, it's on the second Monday in June. In Western Australia, the Governor decides on the date of celebration depending on school terms and the Perth Royal Show.

In Britain, her birthday is celebrated on the second Saturday of June. While most New Zealanders enjoy the day off - or the perks of working a public holiday - the Queen's birthday is not a public holiday in her own country of birth.

None of these dates are the Queen's actual birthday, which is April 21.

The idea of the June birthday is that celebrations can take place on a Saturday when England's weather is at its best.

This makes less sense in Australia and New Zealand, where the birthday is celebrated during the deepest stretch of winter.

The Queen is the employer of all government staff - even in New Zealand

All government staff  including parliamentarians, police officers, members of the Defence Force and judges  are employed by the Queen.

The monarch, as the living embodiment of the Crown, also owns all Crown lands and state-owned companies (Crown entities).

In New Zealand, the Queen appoints a Governor-General to serve as her representative. At the moment, that representative is Rt Hon Dame Patsy Reddy. That appointment is made at the recommendation of the Prime Minister of New Zealand.

She also creates Lords, forms governments and is head of the Church of England.

She can vote

There's a persistent rumour that the Queen cannot vote. She can - but she reportedly never has.

She has her own private cash machine

Buckingham Palace has been the official home of the monarchy since 1837. It has more than 700 rooms, including 52 royal and guest bedrooms, a swimming pool, a doctor's surgery and a post office.

The royal family also has its very own cash machine. It's kept in the Buckingham basement and is reserved specifically for their use.

The Queen signs bills into law - and has veto power

When bills have passed through the two British houses of Parliament, the Queen signs them into law.

Although the Queen could technically refuse to sign a bill into law, she's unlikely to ever exercise that power. The last monarch to refuse their signature was Queen Anne. That was in 1708.

A power that is more frequently utilised, however, is "Royal Assent." The Queen can only exercise this power under the advice of ministers, but it's been criticised as "secretive".

"Royal Assent" is permission given by the Queen before bills that could affect the Crown's interests are debated in Parliament.

A Guardian investigation in 2013 found the power was used to veto a private member's bill that would have transferred the power to authorise military strikes against Iraq from the Crown to Parliament.

That bill was vetoed in 1999, but the information was only released  after Downing Street lost a legal battle.

Along with the rest of the royal family, the Queen is exempt from Freedom of Information requests.

She doesn't have to pay tax

In 1992, the Queen voluntarily began paying taxes. The Labour Opposition at the time insisted she was "forced" into paying taxes as a result of pressure from outside the Palace.

We don't know how much the royal family earns, or how much tax they pay. We will probably never find out, either, thanks to the royal family's exclusion from the Freedom of Information Act.