LONDON/MALABO - Freed British mercenary Simon Mann said his homecoming was the most wonderful he could have imagined, after earlier expressing relief that his West African coup attempt had failed.

The former special forces officer, who touched down in a private jet at Luton Airport north of London, issued a short statement through a spokesman but did not appear in person.

There hasn't been a moment during the last five-and-a-half years where I have not dreamt of one day being back in Britain with my family, his spokesman said on his behalf.

I'm hugely grateful to President Obiang for releasing me, it's the best, best, early Christmas present my family and I could ever have possibly imagined, he said.

He called his arrival the most wonderful homecoming I could ever have imagined.

Equatorial Guinea pardoned Mann this week on health grounds after he had served just over one year of a 34-year sentence for a 2004 coup attempt on the oil-producing nation that was foiled when he was arrested in Zimbabwe.

Mann, who said he had spent five-and-a-half years in solitary confinement, asked to be given time to adjust so that he could spend time with his family.

I'm especially looking forward to meeting my son Arthur, who was born a few months after I left the country and who, consequently, I have never seen.

British counter-terrorism police said they were looking into the coup plot to see if there were grounds to bring charges against the coup planners in Britain.

There is an investigation going on to establish whether there were any offences disclosed in this country in relation to the events in Equatorial Guinea, a spokesman for London's Counter-Terrorism Command said.

Mann was pardoned by President Teodoro Obiang Nguema Mbasogo weeks before an election in which Obiang is expected to seek and win a new mandate to lead sub-Saharan Africa's third largest oil producer, which he has ruled since toppling his uncle in 1979.

Analysts and diplomats have said that Obiang had little to gain from holding Mann any longer, and probably pardoned him to try to improve his image.

Obiang's government has been criticized for rights abuses, including the torture of political prisoners and criminals, and the mismanagement of vast oil riches. Transparency International ranked his country the ninth most corrupt in the world in 2008.

Mann, who spent more than three years in prison in Zimbabwe before being extradited to Equatorial Guinea last year, said earlier he had been treated more like a guest than a prisoner and thanked the president for paying for two hernia operations he needed.

Now I am relieved that the coup d'etat we tried to lead in 2004 was not successful, Mann was quoted as saying.

Four South African accomplices of Mann were also pardoned this week, their release coinciding with a visit by South African President Jacob Zuma.

South Africa in a statement welcomed the release of its four nationals.

(Additional reporting by Michael Holden)

(Reporting by Stefano Ambrogi and David Lewis; editing by Tim Pearce)