THE long-running battle by a father to establish how his son died after his body was discovered in a Thurrock farmyard 20 years ago has returned to a courtroom.

Les Balkwell believes that the circumstances of the death of his son Lee have not been properly established and he has been challenging the opinion of Essex Police, who deemed the death to be a 'tragic accident' ever since the 33-year-old's body was found between the drum and chassis of a cement mixer at Baldwins Farm in South Ockendon early on 18 July, 2002.

Mr Balkwell senior believes his son was unlawfully killed and his body placed in the machine in a bid to make it look like an accident. His opinion was backed by a 2008 inquest which ruled Lee had been 'unlawfully killed'.

Essex Police has apologised, made admissions and paid compensation to the Balkwell family over failings in its original investigation.

However, Mr Balkwell's calls for a further inquiry into the circumstances of his son's death have gone unheeded by police.

He claims Essex Police's decision not reopen an inquiry into his son's death is "unlawful" and "irrational."

Mr Balkwell has made 130 complaints to the police complaints bodies and in 2012 a Police Complaints Commission report said Essex Police's investigation was "seriously flawed".

The High Court heard this week that Mr Balkwell senior had progressed his case "through his own sheer determination" after a "very hard battle" and following the "systematically flawed" work of Essex Police, which had closed its mind to the possibility of murder".

Judges Dame Victoria Sharp and Mr Justice Bennathan are expected to deliver their judgment at a later date.