The scene of the protest is hundreds of metres away from where Buhari is meeting with Commonwealth leaders.
According to a report by TheCable, the protesters are requesting for the release of Nnamdi Kanu, the leader of the Indigenous People of Biafra (IPOB), who has been missing since September 14, 2017.
IPOB has always maintained that Kanu was abducted by troops of the Nigerian Army for his fight for the realisation of an independent Biafran Republic.
The scene of the protest is hundreds of metres away from Buckingham Palace where the president is meeting British Prime minister, Theresa May, and other heads of state in the Commonwealth.
Nnamdi Kanu has not been seen in public since an alleged attack on his father's compound by soldiers on September 14, and has missed a few court appearances since then. His parents, HRH Eze Israel Kanu and Lolo Sally, have also been missing since then.
His counsel, Ifeanyi Ejiofor, stands by his claim that he's in custody of the military while the government has always maintained that Kanu has gone into hiding to avoid prosecution with other rumours circulating that he might have even escaped to the United Kingdom.
He was arrested by the Department of State Security (DSS) in 2015 and spent two years in custody until he was granted bail on health grounds in April 2017.
Due to the events that happened in September when IPOB members publicly clashed with soldiers, the activities of the group has been proscribed and it has been branded a terrorist organisation.