P156 CEEFAX 156 Sat 16 Apr 17:28/14  BBC SPORT  African runners will bid to break the European stanglehold of the London Marathon tomorrow. British and Norwegian runners dominated the first two races, but the decision to incorporate the AAA Championships has attracted a top class international field. The man the leading runnjts fear is Tanzania's Leodgar Martin, who has a best time 2 hrs 13 mink. A record 18,000 runners will take part in the 26-mile race from Greenwich to Westminster Bridge.  Sport headlines 140 