"We have a lot of questions, and somebody needs to answer them," the daughter of murdered Conservative MP Sir David Amess has said.

Katie Amess told the BBC Radio 4 Today programme that the authorities had failed to adequately protect her father and her family wanted an investigation.

Ali Harbi Ali stabbed the Southend West MP to death during a constituency surgery in Leigh-on-Sea, Essex, on 15 October 2021. He is in jail serving a whole-life prison sentence.

The Home Office and Essex Police said it was inappropriate to comment because of ongoing legal proceedings, referring to legal action Ms Amess began earlier this year.

Speaking to Today's Mishal Husain, Ms Amess said: "Nobody is being given any answers... so that we can learn from our mistakes and make sure this doesn't happen again. "

She said there were questions as to why police did not respond to protect her father when an immediate threat had been reported.

She said her brother had received a phone call the night before the attack, saying Sir David, 69, was going to be killed and that this was reported to the police.

The call was later found out to be from unrelated parties - but Ms Amess said that does not matter because they "should have gone" to Sir David's constituency surgery the following day.

"Just one threat should be enough for you to go and protect somebody."

She added: "If they were there, my dad probably wouldn't be dead.

"And I think we need to have a full investigation into why they didn't show up, and people need to know the answers to this so that we can prevent it happening again."

Essex Police said it had immediately launched an investigation following the phone call and a woman and man were arrested. It said like all police forces, it does not provide officers to police MP constituency surgeries.

"This incident and the murder of Sir David were not linked in any way," the force added.

Ms Amess is also calling for a full investigation and disclosure of how Ali - who was convicted of the murder and sentenced to life without parole in 2022 - fell through the cracks of national security.

During the trial, it emerged that Ali had been referred to the government's counter-extremism programme, Prevent, in 2014 and 2015 when he was a teenager.

Essex senior coroner Lincoln Brookes decided in July not to resume Sir David’s inquest, which had been adjourned once Ali was charged with murder.

In a report explaining his decision, he said there was so much of a gap between the Prevent intervention and the murder of Sir David that there was "no evidential basis to consider this attack was possibly preventable so many years and imponderables later."

But Ms Amess dismisses that, saying: "Why on earth would you not want an inquest into this?

"The point of Prevent is to track down terrorists and stop them before they carry out their attack. That is what Prevent is meant to do.

"The police had a phone call the night before, why on earth would they not go to the surgery the next day?

"There's so many people that are at fault here, and nobody is being given any answers, because I'm not being allowed a full public, open inquest, so that we can learn from our mistakes and make sure this doesn't happen again."

High Court papers show that Ms Amess, an actress who lives in California, filed a personal injury claim against the Home Office and Essex Police in December.

But she told the BBC: "I can't actually do the civil claim, because that would cost, like, hundreds of thousands of pounds that obviously I don't have.

"So my only hope was to do this inquest, and that has been taken from me."

Essex Police said it was aware a claim form had been filed at court, but "as these papers have not been served on our force, we are unable to comment any further upon them".

The force added that Sir David had been a "heroic public servant" and "in the immediate aftermath of his murder, two of our heroic unarmed officers ran into the face of danger, trying desperately to save him and of course detaining his killer.

“Several other of our officers attended shortly afterwards and worked with paramedic colleagues to help save Sir David, sadly they were unable to do this."

It added that it regularly reviewed and advised around security arrangements for the county's MPs.

“If information or intelligence comes to light to give us cause for concern of the safety of an MP we would of course advise and guide them to keep them safe and provide a policing presence where necessary."

The Home Office said Prevent was a vital tool in tackling terrorism.

"The attack on Sir David Amess was an awful tragedy, the safety of members of Parliament is paramount and significant work has been taken forward in response to his tragic killing," it said.

Ms Amess also paid tribute to her father as "the most hardest-working person I've ever met", describing him as someone who loved helping people and who was "full of life and enigmatic and passionate".

She said it was now "so hard" for her to be in Southend "because it just reminds me of my father".

"I just wish that he was here to see all of this and to see Southend as a city."