Kent's Royston has joined artists around the world by responding to the attack on French satirical magazine, Charlie Hebdo, with a cartoon.

Twelve people including Charlie Hebdo editor Stephane "Charb" Charbonnier, and two police officers, were murdered when gunmen attacked the magazine's Paris offices.

Another eight were injured, four seriously.

In the aftermath of the attack cartoonists flooded social media with defiant, satirical images.

Mr Robertson, who produces cartoons for Private Eye, The Spectator and the BBC, in addition to the KM Group's newspapers, said the attack was "completely out of proportion."

He told KentOnline: "What we're talking about here is some cartoons, some drawings, and the fact that people could lose their lives over that is just awful."

"The saddest thing of all would be if everyone just clammed up and didn't approach this and other difficult subjects. That's what editorial cartooning is for" - Royston

The cartoonist said he does consider the anger his work could provoke, but does not let that prevent him taking on difficult subjects.

"You consider it all the time. As a cartoonist I don't go out of my way to deliberately defend people, I think most cartoonists don't go out of their way to deliberately offend people, but sometimes it's unavoidable in order to make a point, and you should never expect a reaction such as that we've seen today.

"The saddest thing of all would be if everyone just clammed up and didn't approach this and other difficult subjects. That's what editorial cartooning is for.

The reaction to the attacks was marked by mass demonstrations of solidarity across France, with thousands of people filling squares in Paris, Lyon, Toulouse and other French cities.

Crowds also gathered in Trafalgar Square in London last night as people sought to show their support for the victims' families and friends, and for press freedom in the face of extremism.

Mr Robertson said: "Most people have been quite measured, and there have been some very good cartoons in response to it, particularly one by David Pope, the Australian cartoonist who did a very straightforward picture of a terrorist shooting a cartoonist and saying 'he drew first'."

Mr Robertson focuses mainly on home affairs, but says it's important that whatever the subject, people should be free to satirise and question without fear of violent reprisal.

"I do some political cartooning. I've recently done some local political cartooning with Ukip and things. I don't do a great deal on international politics if you like, but that's not really the point.

"The point is if I did, I was doing that without fear of the awful things that have happened today."