It has prompted the Labour peer, who is blind, to demand action on what he is calling “death trap” platforms.
He told the Sun on Sunday about the incident when he was attempting to board a London Underground train on the District Line three weeks ago with his guide dog during rush hour.
“As I took a step to get onto the Tube train I suddenly felt both my feet disappearing down the gap. Looking back, I must have lost my footing because ‘the gap’ between the Tube and platform was so large,” he said.
He said he suffered “excruciating pain” in his legs and “was really worried.” He added: “I recently had a heart attack… any bleeding or bruising is dangerous.”
An X-ray confirmed “extraordinary bruising” but no broken leg, and he says he is “angry” about what happened.
“Whenever you step into a Tube station in London you hear the tannoy warn people to ‘mind the gap’. But too often there are no staff members to actually help you if – like me – cannot see.”
He called on Transport for London (TfL) to do more to keep visually impaired people safe, including identifying platforms with the largest gaps and narrowing them.
“The day of my accident the staff member who was meant to be attending the platform had been called away because someone had been attacked.
“Clearly, it is vital that there should always be someone on hand, especially during rush hour. Some of our platforms are death traps.”
Nick Dent, London Underground’s director of customer operations, said: “We were extremely sorry that Lord Blunkett was injured on our network.
“We have written to, and will be meeting with, him to discuss how we could have managed the incident better and to ensure that lessons are learned.
“The safety of our customers and staff is at the forefront of everything we do, and while injuries like the one experienced by Lord Blunkett are rare, we are undertaking a huge range of work aimed at eradicating such incidents and making travelling even safer for everyone.”
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Lord Blunkett added that he does not easily get scared.
“I have been navigating Britain’s streets and stations with my guide dog for decades. But that day I was spooked.”
“How many others have fallen and been seriously injured because of the gap? We need action now to avoid preventable injury or worse,” he said.