London's Mayor Sadiq Khan: More attacks 'highly likely'...and I have a terrible "what if"

A week or so ago British security/intel agencies gave the number of terrorists in their country which totalled to a reinforced division of troops.

What if?  What if this is ISIS inspired and they are planning on a summer of attacks?  What if the plan is for let's say 10 cells initially to launch attack after attack.  They know to go operational a few days after the prior cell attacked a target.

It's obvious that the authorities are walking a self imposed tightrope. If they attempt to get ahead of the situation now, it will take draconian measures that will stuff their economy and the Brits can't afford that.  If they don't then they face further terrorists attacks which will stifle their economy and cause the current govt to fall.

The politicians MIGHT have painted themselves into a corner by not acting more aggressively sooner.  It reminds me of an old saying.  Inaction is an action.  They failed to act and now the butchers bill is coming due.