"From Mrs May's point of view, it's very hard for her to suggest anything radically different because of course she's been in charge of security policy for the last seven years, either in overall charge or as home secretary", he said.
Tougher laws and police powers may fail to prevent low-technology attacks, such as the two van-and-knives assaults that occurred in London, and may well end up alienating British Muslims, he said.
"I mean longer prison sentences for people convicted of terrorist offences".
Mrs May said she would make it easier to deport foreign terror suspects and "restrict the freedom and movements" of those who present a threat.
May explained other stringent measures would include easier deportation of foreign terror suspects to their own countries and restriction of the freedom and movements of terrorist suspects once there is enough evidence to know they pose a threat - but not enough to try them in court.
"If our human rights laws stop us from doing it, we will change the laws so we can do it", she said to cheers and applause at an election rally.
'If I am elected as Prime Minister on Thursday, that work begins on Friday'.
It also says: "We will remain signatories to the European Convention of Human Rights for the duration of the next parliament".
The election campaign has been largely focused on national security in the wake of Britain's third major terror attack this year.
The security services have come under pressure after it emerged one of the attackers, Khuram Butt, 27, had been reported to the anti-terror hotline in 2015.
Dr Sally Leivesley, managing director of Newrisk, a London-based risk consultancy, said a critical issue for the United Kingdom government is to legislate in such a way that behaviour and intention to act against the state fall within the law and can lead to prosecution. "We have to protect our basic freedoms, our basic democracy and our human rights", he said.
"In her years as home secretary she was willing to offer up the police for cut after cut".
He said the PM's plans "would potentially give the police more powers to control people who there might not be enough evidence to bring to court". In her remarks, she announced a review of counterterrorism policy, harsher sentences for terrorism offences, and an effort to crack down on "safe spaces" online and in self-segregated Muslim communities that can harbour extremism.
"If Theresa May does what she threatens, she will go down in history as the Prime Minister who handed terrorists their greatest victory".
Earlier the London Mayor, Sadiq Khan, put himself at odds with her as he claimed that a planned spending squeeze on the Metropolitan Police could lead to the loss of thousands of front-line officers.
"Our city has suffered two very bad terrorist attacks since I was elected as mayor - and we must do everything possible to stop there being any more".
"The police and security services must get the resources they need, not 20,000 police cuts".