Please correct me if wrong...but I think this is the first flight to operate as a through service with the same flight number LGW-Baghdad with MMX as a glorified tech stop (also happens to be where Tor Air are based, so can easily exchange crew etc).
I was under the impression that all Viking flights had change of flight number and full commercial stops in Sweden (presumably they have to do this as traffic permits for a non-UK/non-Iraqi carrier as a through route might also be something of an issue...regardless of whatever the DfT makes of it!)