She remembers him as a loving, lively father but also a reclusive character, to be feared and avoided.

However, despite enduring years of his unpredictable behaviour, Ms Horsnell could never have foreseen she would find herself fighting to free her father from death row in a Chinese jail.

In September 2007, Akmal Shaikh was arrested in Urumqi, north-west China, as he arrived in the country. In November 2008, Shaikh was convicted of drug smuggling and sentenced to death. On Tuesday, Chinese executioners will put him to death by firing squad. It looks increasingly unlikely that he will be shown clemency. In China, the corpses of executed prisoners are sometimes harvested for organs.

His family last night begged the Chinese Government to release him from prison, citing his diagnosis of

bi-polar disorder and insisting that he had no idea the suitcase he carried into the country was packed with cocaine.

“It is like a dream or a film script.” Ms Horsnell said. “Growing up, my father was very difficult and suffered severe mood swings but we didn’t realise he had a psychiatric disorder until much later. We could never have known he would end up in a situation like this. His chances do not look too good at the moment. It feels like the Chinese Government are not taking into account just how severe his mental illness is.”

From Kentish Town, north London, Shaikh married and had three children: Ms Horsnell, 31, and her two younger brothers, Abdul Jabar Shaikh and Imran Shaikh. Ms Horsnell, a GP practice manager, describes her childhood as predominantly happy, but one marred by her father’s odd behaviour. He would, she says, encourage them to see extended family and make friends before banning them from speaking to people outwith the family home.

The taxi firm owner would be gregarious for months on end before becoming reclusive, saying he, his wife and children should be self-sufficient. Once, Ms Horsnell remembers, her younger brother broke his arm in three places. At the hospital, Shaikh declared he knew best how to treat the break and refused the surgeon’s advice to secure the bones with metal pins. Instead, he insisted the boy’s arm should be put in traction.

Shaikh’s marriage to his first wife eventually broke down and in 2001 he moved to Poland where he remarried and had two more children. His family lost touch with him and, in Poland, his mental condition worsened.

The 53-year-old ended up living on the streets where he became known to a local drugs gang. The story took an increasingly bizarre turn as Shaikh, said to be increasingly delusional, penned a song about rabbits, which he was convinced would become a world-wide hit and usher in world peace.

Members of the drugs gang allegedly told Shaikh they would record his song and make him a star in China, if he would accompany them there.

According to Shaikh, at the airport the drug runners told him there was only one seat left on the plane and encouraged him to take it, and carry their suitcase with him. Inside was 4kg of cocaine. Human rights charity Reprieve has taken up Shaikh’s case, petitioning the Chinese Government and the United Nations Special Rapporteur Philip Alston. Broadcaster and actor Stephen Fry is also championing the father-of-five’s right to life.

Sally Rowan, legal director of Reprieve’s death penalty team, said: “We have to keep hoping until the last minute. We are not above begging at this point. We have never been able to see Akmal or speak to him so we cannot judge his mental state at the moment and we are unsure whether he is even aware that he is to be executed.”

A report from Dr Peter Schaapveld, a forensic psychologist, said it was probable that Shaikh’s behaviour was “influenced or caused by” his mental illness. Shaikh’s behaviour during his imprisonment has, claim Reprieve, offered further proof of his instability.

He refused legal representation at his trial, instead choosing to defend himself, but appeared rambling and incoherent in court. UK consular officials have visited Mr Shaikh several times in prison and attended relevant trials, although his family has had no contact with him. The Chinese, however, seem steadfast in their decision to proceed with the execution. In a statement, the Chinese embassy claimed the amount of cocaine Shaikh was carrying would cause 26,800 deaths.

The statement read: “The concerns of the British side have been duly noted and taken into consideration by the Chinese judicial authorities in the legal process, and Mr Shaikh’s rights and interests under Chinese law are properly respected and guaranteed.

“We fully respect the UK and EU’s decision to abolish the death penalty. However, half of the countries in the world still maintain the death penalty. In China conditions are not yet met for abolishing the death penalty. The majority view is against such abolition. The death penalty is applied in a cautious and strictly limited manner.”