Could an English 'granny' be an al-Qa'ida terrorist?

One wonders if this is what the French police were thinking when they stopped a bus carrying members of a Women's Institute (WI) group from Suffolk from entering the Channel Tunnel when they were returning home from a trip to Paris to celebrate the 85th anniversary of their WI branch. What a good camouflage it would be, though, if one of these 'Miss Marple' types was in fact a ruthless suicide bomber. More likely, I suppose, was a worry that some nefarious group had planted explosives aboard the bus whilst it was unattended in 'The City of Light'. I bet many strong cups of tea were drunk by these ladies when they finally reached home.