The government cannot be held legally liable for abuses during the Mau Mau rebellion against British colonial rule in Kenya, a court has heard.
The claimants, Ndiku Mutua, Paulo Nzili, Wambugu Wa Nyingi and Jane Muthoni Mara, who are in their 70s and 80s, have flown from their homes in rural Kenya to appear in court.
The judge heard Mr Mutua and Mr Nzili had been castrated, Mr Nyingi was beaten unconscious in an incident in which 11 men were clubbed to death, and Mrs Mara had been subjected to appalling sexual abuse.
Mr Mutua, 78, told the BBC his castration had affected his "psychological being".
"Being a man without a family, without a wife, is so shameful and I live under shame even with my peers," he said.
Standing with his clients on the steps of the High Court on Thursday, Mr Day said they were primarily seeking an apology.
"They were subjected to unspeakable acts of torture and abuse at the hands of British officials in the 1950s and 1960s, including castrations, sexual abuse and repeated beatings," he said.
"The treatment they endured has left them all with devastating and lifelong injuries. There is no doubt that endemic torture took place in Kenya before independence."
Mr Jay, for the foreign secretary, said the role of the regular forces of the British Army was to fight the battle against the Mau Mau in the forests but they played no part in the "screening" activities - a system of interrogation to identify suspects - within the camps.
He rebutted the claim that the liabilities of the colonial administration passed to the UK upon Kenya's independence in 1963.
Mr Jay also argued the case was not valid because of the amount of time that had passed.
Death toll
Archive searches connected with the case have led to the discovery of thousands of files from former British administrations, including some about the Mau Mau uprising, which are to be made public by the Foreign Office.
David Anderson, professor of African politics at Oxford University, who has examined some of the withheld documents, said the files proved Whitehall not only knew what was being done to Mau Mau suspects but also had a part in sanctioning their ill-treatment.
An official report in 1961 determined that more than 11,000 Africans, most of them civilians, and 32 white settlers died during that period.
