"Deghayes and Banna arrived back in Britain with a third British resident, Abdennour Samuer. Banna, from north-west London, was arrested in the Gambia in 2002 after he did not accept an MI5 request to become an informant.

Irene Nembhard, a lawyer for the men, said it was time for them to be allowed to rebuild their lives."
...Guardian

How awful, those poor men

My impression is that it's done to them to prove it can be done probably as an example but the guilt or innocence of the victim is irrelevant. Like torture is done not to extract information but make the victim compliant like in the Stalinist show trails. Of course the sick minds, getting sicker by the day, of the perpetrator is another factor.

Just as rape is not about sex, torture is not about "information gathering."

It's about control, power and domination. Period.