Manchester attack: As bombs return, what can be done to make venues safer?

The threat in UK is at level 4 - indicating that an attack is 'highly likely' or 'severe'

The bomb attack on Manchester Arena comes at a time when the whole of the UK is on high terror alert. Across Europe, there recently have been a number of attacks using vehicles and knives – and that has focused many people’s minds on these being the types of terrorist assault to expect. But Manchester has now taught us that we should never forget the acute danger presented by bomb attacks.

Only last year we saw bombs in Brussels, Belgium, and Aachen, Germany. With the UK at threat level