The people of Gibraltar have voted in a referendum on whether the UK and Spain should share sovereignty of the territory - and issued a resounding No. BBC News Online answers the key questions.

Does the referendum result mean anything?

The result - a 98.97% No to shared sovereignty - will carry no legal weight.

Spain's foreign minister has said the result has no value, because it is a "largely virtual" vote based on a hypothetical agreement.

London also says the vote has no legal weight.

But the Gibraltar authorities believe it will send a powerful signal to London and Madrid that joint sovereignty is a "political dead end", as Chief Minister Peter Caruana put it.

What exactly were people asked?

The question on the paper was: "Do you approve of the principle that Spain and the United Kingdom should share sovereignty over Gibraltar?"

Just 187 people voted Yes, as compared with 17,900 who voted No.

Where did this idea spring from?

The proposal to share sovereignty, under negotiation by London and Madrid, is an attempt to bridge an apparently unbridgeable gap between their two positions.

Spain has traditionally claimed full sovereignty, as has London.

The idea of sharing the territory was seen as a possible way of breaking the deadlock, but residents - led by Mr Caruana - remain implacably opposed.

It is Mr Caruana who organised the referendum, to prove to London the strength of feeling.

What exactly have the two governments been talking about?

When talks began in 2001, the two governments agreed to work towards a "complete agreement" on the Rock's future by the summer of 2002.

The negotiations were undertaken on four "pillars": respect for Gibraltar's way of life, greater co-operation, extended self-government and joint sovereignty.

The process got under way with official declarations of optimism that the centuries-old dispute could finally be laid to rest.

So what went wrong?

The summer target was missed as talks became bogged down, mainly on the sovereignty question.

Both the Spanish and UK governments have acknowledged that "real differences" remain over the way forward, despite their early optimism.

The UK wants any settlement to be a permanent deal, but Spain is refusing to give up its hope of one day regaining full sovereignty.

Spain is worried that accepting joint sovereignty now could, in effect, blight its chances of achieving full sovereignty later.

Another stumbling block has emerged, over access to Gibraltar's naval and air base.

So how will the deadlock be broken?

At the moment, the squaring the circle looks impossible.

Spain says full sovereignty is non-negotiable.

The UK is willing to consider shared sovereignty, but insists no change can take place unless residents vote for it.

UK leader Tony Blair and his Spanish counterpart Jose-Maria Aznar have a close working relationship, but it is hard to see how even their partnership can take the process forward.

What are the rewards of solving the problem?

Both the UK and Spain are keen to resolve for good the long-running dispute which has become increasingly problematic in EU relations.

Some also say it would open the way for an Anglo-Spanish axis within Europe, to rival the Franco-German alliance.

How long have Britain and Spain been squabbling?

The Rock has been fought over for centuries. First it was Spain battling Moorish invaders. Then, after several hundred years, the Spanish lost Gibraltar to an Anglo-Dutch force in 1704.

The Spanish - despite formally ceding it to London in the 1713 Treaty of Utrecht - have wanted it back ever since.

More recently the battles have been political. In 1984 the two governments started talks, but the process eventually collapsed over Madrid's demands that the Rock should revert to full Spanish sovereignty after 50 years of shared control.

Under Franco, Spain cut Gibraltar off by sealing its frontier. The border was eventually reopened 16 years later, in 1985, but delays remain lengthy for anyone wanting to cross it.

What's actually in Gibraltar?

It's a tiny area, less than six square kilometres (2.2 sq miles). The Rock of Gibraltar itself dominates the area, standing nearly 430 metres (1,400 feet) high.

Despite its size, it is strategically important. It stands at the mouth of the Mediterranean, at the foot of the Iberian peninsula, and only 20km (12 miles) from the north coast of Africa.

It has a Nato base, including a port and airstrip.

Tourists enjoy the cheap alcohol and tobacco available because of the Rock's VAT free status.

And of course there are the famous apes... brought over from North Africa by British soldiers, and now roaming freely on the Rock.

How British are the residents?

Despite Gibraltarians' Mediterranean home and their use of the Spanish language for almost everything but education and administration, their "Britishness" remains central to their cultural identity.

Under a new constitution introduced in 1969, they have a large degree of self-government.

Many Gibraltarians say that were it not for the counter-productive measures introduced by Spain, such as sealing the borders, they would be more ready to consider increased co-operation.

Why is Spain sometimes accused of hypocrisy over Gibraltar?

Spain still holds two enclaves across the Mediterranean in North Africa.

Ceuta and Melilla are almost directly opposite Gibraltar and have considerable parallels.

Both were retained by Spain in 1956 when the rest of Morocco - formerly a Spanish protectorate - was granted independence.

Morocco wants them both but Spain is refusing to budge.