Cleo has eaten 6kg of fish a day

An airline gave her a free lift from Malaga to London.

But a connecting flight to Scotland was cancelled and she ended up being taken by van to the National Seal Sanctuary at Gweek, in Cornwall.

There she has been devouring bucketfuls of fish to get up to a healthy 50kg, ready for the final journey home - wherever that may be.

Mark Steward, curator of marine mammals at the Oban sanctuary, has spent time with Cleo in Cornwall.

He said: "Cleo was 35kg when she first arrived but since 14 November we have been feeding her six kilos of fish a day and she has piled on the weight."

Her final departure point on Sunday depended on the weather, he said.

'Good navigators'

"If the weather is bad we will go across the Pentland Firth to Orkney and let her go on the beach on the north east of the island.

"But if the weather is good we will take her far out to sea, up towards the north of Shetland, where we will let her go off the boat."

Cleo has been nursed at Gweek seal sanctuary

He said the pup would travel to the North Atlantic, possibly to Iceland or Greenland - the precise destination was unknown.

He was optimistic she would make it.

"Seals are good navigators and she only has to travel a couple of hundred miles," he said.

Hooded seals are rarely seen as far south as Britain, let alone Spain.

One was found at Treyarnon Bay, Cornwall, in 1995, and another survived beaching at Little Haven, Pembrokeshire, in July this year.

The species is seen only very seldom on the Orkney and Shetland coasts.

It is not clear how Cleo came to wander so far from her normal feeding grounds in the North Atlantic.

Over-fishing by human rivals may be to blame.

Mr Steward may not have seen the last of Cleo, though.

In 1997, a bearded seal nicknamed Whiskers was released off Shetland after washing up in Lincolnshire.

The next year, he reappeared in Hartlepool, in north-west England.