Del Singh, 39, was one of two Britons who were killed in the devastating attacking at a restaurant in Kabul on Friday.
The attack, which the Taliban quickly claimed responsibility for, left 21 people dead, including senior UN officials, Afghan dignitaries and restaurant staff.
Simon Chase, a former British soldier from Limavady, Co Londonderry, was also killed.
Mr Singh, from Southampton, was due to stand for the South East in May's European elections and was working as an international adviser supporting the Afghan Budget Department in Kabul at the time of the blast.
His family told the Sunday Telegraph he was "funny, big-hearted and humble". His partner, Komal Adris, 35, said he had advised Labour leader Ed Miliband on Israeli and Palestinian policy and travelled regularly to Afghanistan.
She told the newspaper: "He loved the country. He's been going there on and off for around six years. He kept going back to all these conflict areas because he loved his work and wanted to see a more peaceful world."
Mr Singh's sister, Dishi Phangurha, 34, told the Telegraph he had spoken with his family on Thursday, saying: "He was so optimistic so there was no suggestion something like this was about to happen. It's a heavily guarded restaurant."
Tributes poured in for Mr Singh yesterday, with Mr Miliband saying that through his 10 years of development work in countries like Afghanistan, Kosovo, Sudan and Sierra Leone, he had "dedicated his life to working with people across the world who needed his support."
Anneliese Dodds, a fellow MEP candidate for the South East, told the Sunday Times she had exchanged emails with him just a few days ago.
She told the newspaper: "Del was such as warm and friendly person with an infectious sense of humour. Even though we were all competing with one another, everyone got on with him and he enlivened all the hustings."