Britain said on Monday it had revived diplomatic relations with Iran and appointed a non-resident charge d'affaires, two years after an angry mob ransacked the British embassy in Tehran.
The announcement reflects a thaw in relations with the West and comes after Iran and six world powers, including Britain, came close to a preliminary agreement about Tehran's nuclear programme at the weekend.
Britain's Foreign Office said Ajay Sharma, currently the head of the ministry's Iran department, will take up the post immediately.
More top news
Ex-Spitfire pilot Allan Scott, 94, said he was told off by the Queen when he first met her in 1943 when she was just 16.
Last minute preparations are going on at the Church of St Mary Magdalene where Princess Charlotte will be christened.
Princess Charlotte is being christened on Sunday at Sandringham in Norfolk in only her second public appearance since she was born.