The current UK terrorist threat level remains at the 2nd highest.
It would only increase to the highest level if COBRA (Cabinet Office Briefing Room A) decide on the advice of the security services that an attack in the UK is imminent.
It's natural to be worried when our close neighbours have suffered a terrible massacre, plus many previous terror attacks.
Unkind to call someone hysterical for expressing this fear.
However, we can only go about our normal life until advised otherwise.
The Met have listed some of the extra security measures they are taking for London, always the prestige target in the UK; there'll be other measures elsewhere.
So, the security services may well ask for more powers, but although some posters here won't like it, the vast majority of voters are far more worried by terrorists than by having their Emails read.
Did I understand you, username that you think our security services would happily allow hundreds of their fellow Uk citizens to be murdered, in order to gain extra powers ?
I think they'll try their best to stop attacks, which has mostly worked since 7/7, but - like the IRA once said - the terrorists only have to beat them once to get an attack through. And the public will scream incompetence.