Newcastle University's Conor O'Neill, who carried out research into the effects of a bomb blast inside a train carriage, said using special materials could prevent shrapnel injuring passengers.
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The mother of a former altar boy who tried to blow up a train insisted he was 'a big softie' who didn't want to hurt anyone.
Its current five year licence comes to an end next Tuesday.
Extra armed police will guard major sporting events in London this weekend after the military was drafted in to protect key locations.