Tahir Khan, a 15-year-old boy from Clayhall has taken a 50 km run challenge while fasting during the Muslim holy month of Ramadan to raise funds for Covid-19 in the U.K, India, Pakistan, Bangladesh and 45 other countries. On Saturday he joined London Mayor Sadiq Khan and 101-year-old charity hero Dabirul Islam Choudhury, who launched the global walk challenge "Walk with Dabirul" to take steps in his garden in Bow.