If there was no truth in these accusations, which are pretty much internet-born, the PM wouldn't bother mentioning it. Shady.
I'm not debating with anyone on this one it's not worth it, all due respect to the families involved with these supposed murders, but I think the recent decapitations are fake. The USA wants to attack these countries, it wants it's public to back them and it wants the UK to back them.
I think the murders were quite suspect in that you never actually see a murder in any of the videos, they were quite advanced films, not your average homemade death threat, the victims were emotionless. The murderer was so hard to identify, all of a sudden the USA airstrikes 12 oil refineries and within hours it's on the news 'FBI has identified the man behind the beheading, but is not yet prepared to disclose...'.
Shady shit. End of the day those countries are home to families, workers, women and children like any other country, and their skies rained death under the order of America. If the killer in the videos really was identified, there are teams designed for the job; infiltrate and assassinate. Instead they bomb the whole country.