I f Arsenal win the Champions League final later today, expect euphoria across Africa. Judging by the scenes after last week’s Premier League title win – their first in 22 years – the celebrations will be immense. Boisterous fans flooded city centres in Nairobi , Addis Ababa, Kampala and Lagos . In Nigeria’s Zamfara state, people celebrated in the streets despite rising insecurity as a result of Boko Haram’s terrorism. For outsiders, the obvious question is: how did a club from north London become so deeply woven into African popular culture? The most dramatic scenes may come in Kenya, where last week tens of thousands of people – some estimates put the number as high as a million – poured on to streets and highways in a sea of red Arsenal shirts, a sight never witnessed before. Fans climbed lamp-posts, waved flags, sang club songs (including versions composed in local languages) and brought traffic to a standstill.…