Kate McCann shared her one regret that she’ll have 'for the rest of her days' following Madeleine's disappearance

Four years after her three-year-old daughter Madeleine vanished during a family trip to Portugal, Kate McCann opened up on her biggest regret.

The British toddler disappeared from her family's Praia Da Luz hotel apartment back in 2007. Her parents had left she and her younger twin siblings Sean and Amelie at the Algarve property to enjoy dinner with friends at a nearby restaurant on the evening in question.

At around 10pm, Kate returned to the property to check in on her three children, only to find that Madeleine was missing.

In the 18 years since their eldest daughter's disappearance, the couple have fronted numerous campaigns for information on the fate of their little girl, and have even published several written works supplying insights into the heartbreaking ins and outs of the investigation.

The toddler was just three when she disappeared (PA)

In her 2011 memoir - Madeleine: Our Daughter’s Disappearance and the Continuing Search For Her - Kate penned everything she could recall about the evening that her child went missing.

In doing so, the 57-year-old also confessed the 'bitter regret' that she and her husband still bear the brunt of on a daily basis.

In a gut-wrenching entry, Kate explained that she and Gerry had requested a table at the resort's Ocean Club restaurant that would give them full view of their holiday home, in which Madeleine, Sean, and Amelie were asleep.

It wasn't until their eldest was reported missing, however, that she claims she discovered that staff at the restaurant had actually recorded their specific request in their reservation notes, which alluded in written form that there were unsupervised children in the apartment.

"To my horror, I saw that, no doubt in all innocence and simply to explain why she was bending the rules a bit, the receptionist had added the reason for our request: we wanted to eat close to our apartments as we were leaving our young children alone there and checking on them intermittently," Kate wrote.

Kate lifted the lid on her and Gerry's biggest regret (MELANIE MAPS/AFP via Getty Images)

"We now bitterly regret it and will do so until the end of our days."

All eyes have once again fallen on Kate and Gerry McCann this week, following the release of an eerie new Channel 4 documentary shedding light on unheard information surrounding their daughter's notorious disappearance.

Titled Madeleine McCann: The Unseen Evidence, the programme followed an investigation previously carried out by journalists from The Sun newspaper, detailing 'evidence' found in 2016 that allegedly implies that the toddler 'is dead'.

Viewers were shown images of numerous damning artefacts discovered that year in an abandoned factory owned by Christian Brueckner - a German national and convicted sex offender who was first named publicly as a suspect in 2020.

Images found on both a hard drive and several USB sticks were revealed for the first time in the documentary, several of which were of other underage children believed to be aged between four and five years old. A number of masks were also discovered at the property, along with unlicensed guns, children's toys, and as many as 75 children's swimming costumes.

Brueckner was first announced as a suspect in 2020 (Carabinieri Milano via Getty Images)

Though the McCanns haven't yet publicly addressed the documentary, four days ahead of its release, they shared a statement marking almost two decades since Madeleine's disappearance.

"As we arrive at the 18th anniversary of Madeleine’s abduction, we’d like to thank our faithful supporters once again for standing by us and never forgetting about Madeleine," the couple wrote on Saturday (3 May).

"The years appear to be passing even more quickly and whilst we have no significant news to share, our determination to 'leave no stone unturned' is unwavering. We will do our utmost to achieve this."

Elsewhere in the post, Kate and Gerry reminded followers of the case that May is also the month of their daughter's birthday - her 22nd this year.

"No matter how near or far she is, she continues to be right here with us, every day, but especially on her special day," the pair signed off. "We continue to 'celebrate' her as the very beautiful and unique person she is. We miss her."