Former Maldives president Mohamed Nasheed landed in Britain on Thursday, his aide told AFP, after the Indian Ocean islands' government granted him prison leave for urgent surgery.
"We have just landed," said Sabra Noordeen, who was travelling with Nasheed, whose conviction last March on terror-related charges has been widely criticised.
Nasheed arrived at Heathrow Airport, where he is due to meet his lawyer Amal Clooney, wife of Hollywood star George Clooney.
He left the Maldives on Monday for Sri Lanka after resolving a last-minute legal dispute with the government over his 30-day release for the spinal cord surgery in the UK.
He then left for Britain on Thursday.
The Maldives government said Nasheed was travelling under what diplomatic sources described as a deal brokered by India, Sri Lanka and Britain.
But Nasheed refused a government request to leave a relative behind to act as a guarantor liable to prosecution if he failed to return to serve the rest of his sentence.
After a tense back and forth over conditions, the government finally agreed late Monday to let him leave.
His aides said he had held extensive meetings with Western ambassadors in Colombo to discuss the political turmoil on the upmarket holiday island nation.
Nasheed, 48, became the first democratically elected president of the Maldives in 2008 and served for four years before he was toppled in what he called a coup backed by the military and police.
He was sentenced to 13 years in jail on terrorism charges relating to the arrest of an allegedly corrupt judge in 2012, when he was still in power.
The UN has said his trial was seriously flawed and he should be released and compensated for wrongful detention.
But hardline President Abdulla Yameen has refused to accept the UN ruling and has been resisting international pressure to release Nasheed.
Yameen is a half-brother of former strongman Maumoon Abdul Gayoom, who ruled for 30 years until his defeat by Nasheed in the country's first multi-party elections in 2008.
Former Maldives president Mohamed Nasheed (L) is greeted by British lawyer Amal Clooney on his arrival at Heathrow airport in London today. AFP