If you're interested in police history, these websites below can provide you with further information.
British Transport Police History Group British Transport Police History Group is a standalone group dedicated to preserving the history of BTP including all of the railway, canal and dock constituent police forces.
Police Roll of Honour Trust The Police Roll of Honour Trust website lists all UK Police officers who have been killed or died in the line of duty. It has a page dedicated to each UK Police Force.
Police History Society The Police History Society is the official society for the UK. They are unable to conduct individual research but may point you in the right direction. A fee is required to join.