"What firms are still getting to grips with is the preparation – what to do when it happens," says Bird & Bird's joint international commercial head Simon Shooter of the cyber attack that crippled DLA Piper's systems earlier this week.

"In the same way you have planned operation procedures for a fire in the office, you should have your 'speed dial response unit' [in the event of an attack], including PR consultants to deal with external and internal messaging," he adds.