The terrorist in the slickly produced video was quick to link the murder to British foreign policy in Iraq.
The question now for the Government is how to react.
I’ve spoken to a source close to the Prime Minister who insists there will be “no change of policy”, and the killing will only “strengthen our resolve” to take military action against Islamic State militants.
The feeling of a renewed resolve is also apparent among MPs, many of whom took to Twitter to express their anger.
While it seems clear that UK airstrikes in Iraq will continue, it is unclear whether there will be increased pressure to extend them into Syria.
There are some MPs who feel that if Britain wants to get fully involved in the campaign against IS, its strongholds in Syria also need to be targeted. This is not, after all, an organisation that respects countries’ borders.
Either way, as the Defence Secretary has already warned, this is a conflict that could take years to resolve.
There is another aspect to the murders that is impossible to ignore: the man who styles himself as the killer in the videos speaks with a distinctly British accent.
Hundreds of British nationals have travelled to Syria and Iraq in order to fight.
The Prime Minister and the Deputy Prime Minister talk about eradicating the terrorist threat of IS.
If they are serious about eliminating the extremists, they may have to look at home as well as abroad.