The case is being heard at the Court of Session

They claim that the castle - which was sold by their grandfather Ninian Brodie, the 25th Brodie of Brodie, in 1978 - is rightfully theirs.

The clan, which is one of Scotland's oldest aristocratic families, has lived in the property for 800 years.

However, it was sold to the Scottish Secretary of State in 1978 before being transferred to the National Trust for Scotland (NTS).

The siblings, who cannot afford legal representation, also argued that the castle was also sold "under value".

They claimed it was valued at �152,000 in 1974, but was sold for �130,000.

'Breach of trust'

Alexander Brodie, the future head of the family, estimated that it would actually have been worth about �220,000 in 1978 due to inflation and increasing property values.

The siblings told Lady Smith that the sale - which took place when they were aged nine, eight and two respectively - was a breach of trust.

Phaedra said: "We feel the property was sold under value and that the sale benefited the trustee (her grandfather), benefited the second defender (NTS) and the first defender (the then Scottish Secretary of State).

"We feel that this led to our interests being sacrificed to further their own interests.

"We feel that their was some collusion between the three."

Home contents

Mr Brodie said his grandfather, who still lives in Brodie Castle as a guest of NTS, had sold furniture and heirlooms in the house for �275,000 to Christie's auction house in London.

He argued that the 90-year-old had brought down the value of the home by selling the furniture.

But Lady Smith told him that the contents of a house were not regarded as part of the property in law.

The action is being defended by the Scottish Secretary, NTS and others - including their grandfather.

The hearing continues.