The attacks in Paris on the offices of the French satirical newspaper Charlie Hebdo and later at the Parisian kosher supermarket were an attack on what all of us who value democracy hold dear.

It was an attack whose existential response demands all of us to stand up for what we believe in. Paradoxically, and as shown by the mass reaction in Paris on Sunday, it may have been an attack too far.

People who may have condoned book burning in the past are by this action obliged to make the decision about which side of the Rubicon they stand on. Are they for freedom of expression or not?

The fact that a number of the murdered police were themselves Muslim and of North African descent makes this all the more poignant. Both in France and here in the UK people will have been revolted by the murder of 17 innocent people, not only peacefully going about their lives but, for the cartoonists at Charlie Hebdo, engaged in questioning and provoking, bringing life to democracy.

My grandfather, Denton de la Cour Ray, was a cartoonist and a professional soldier who saw first-hand the folly of war and put pen to paper to portray it.

He served in the British Army in both the Boer war and in France during the First World War and a number of his cartoons of those conflicts were published at the time.

Cartoons which question and criticise are part not only of our heritage, but of our present and our future. They are necessary because of their ability to pose questions, capture people’s imagination and then provoke people to share those thoughts. Vive la liberté!

Dr Brian Mathew, Liberal Democrat Prospective MP for North Wiltshire.