I would be very surprised amazed if gateline staff didn't have some form of audio / audiovisual communication with other station staff who, if not already there, could be instructed to meet the passenger on the platform.

Not exactly rocket science?

Not sure that gateline staff are allowed off the gateline are they? - except in cases of emergency.

David Blunkett and his guide dogs

David Blunkett has been blind since birth. He entered politics after his father, Arthur Blunkett – a gas foreman – suffered a fatal accident at work; he was past retirement age and his empoyer refused to provide his dependants with a pension.

Mr. Blunkett became Sheffield's youngest councillor in 1969, at the age of 22. After seven years as Leader of Sheffield City Council (1980-7), he served for 28 years as an MP. He spent a total of eight years in Tony Blair's cabinet: four as Education Secretary (1997-2001), three and a half as Home Secretary (2001–4), and six months as Work and Pensions Secretary (2005).

His first guide dog, Ruby, retired in 1978. She was followed by Ted, a.k.a. Teddy (1978–87), Offa (1987–94), Lucy (1994–2002), Sadie (2002–2011) and Cosby (from 2011).

Ruby was the first dog to be allowed inside the House of Commons, when she and Mr. Blunkett visited in 1971. Sixteen years later, Ted became the first guide dog to grace the floor of the Commons after his owner was elected as MP for Sheffield Brightside.

Teddy, according to Mr. Blunkett, was "a gentle giant of a dog who used to snore under the table during BBC1's Question Time, back in the days when Robin Day was chairman." He also made his presence known by lapping water.

Mr. Blunkett also told how Teddy "brought up his breakfast" during Nigel Lawson's budget speech in 1988. "The Honorable member for Bolsover" (Denis Skinner) asked who was going to clear up the mess – leading inevitably to quips about whether he meant Teddy's breakfast or the UK economy.

If Ted was a memorable character, his successor – Offa – seems to have been the most accident–prone of them all. In a relatively short career, he was sick while Labour's Shadow Environment Secretary Bryan Gould outlined his party's proposals for an alternative to the Poll Tax; suffered a violent allergic reaction when Tory MP Nicholas Fairbairn showered him with snuff at the entrance to the Chamber; and was struck by a van after bolting into the road to escape fireworks near his master's home.

It was Lucy that accompanied Mr. Blunkett through the culmination of his rise to high office, and she was not immune to accidents in the House of Commons. In 1999, when David Willetts (Conservative, Havant) was on his feet, criticising Mr. Blunkett's record as Home Secretary, Lucy was violently sick. This time, as Hansard reports, it was Mr Don Foster (Conservative, Bath) who quipped"I [...] think it rather appropriate that, while the hon. Gentleman was speaking, the Secretary of State's dog was sick." Lucy was rebuked by the Speaker.

Saint Lucy is the patron saint of the blind and partially sighted, the story being that her eyes (like those of many Christian martyrs) were gouged out prior to her execution. I'm not sure whether this was the inspiration behind the name of Mr. Blunkett's arguably most famous dog, or not.

Mr. Blunkett retired from parliamentary duty in 2015. He joked about how he and Cosby were "bow–wowing out".

© Haydn Thompson 2017

.....and their need may not be immediately visible to staff, especially in a crowded Underground station.....

Lord Blunkett does refer to a more practical solution – staff being available to help. Perhaps officially there are, but clearly that solution didn't pan out here. It may be difficult for someone with limited or no vision to find help, and their need may not be immediately visible to staff, especially in a crowded Underground station. Staff helping out does seem to be the best solution here, though.

It is worse than that.  Reborn the tunnels to have straight tracks.

Rebuild the station to have straight platforms.

Are there any alternatives I have missed, or have I overcomplicated them?

From the BBC:

Lord Blunkett has called for an urgent review into what he described as "death trap" Tube platforms after he was injured falling into a gap as he boarded a train at Westminster station.

It happened as the Labour Peer, who is blind, slipped while getting on to a District line train with his guide dog, last month. He wants Transport for London (TfL) to do more to ensure visually impaired people are kept safe.

"I didn't fully know what had happened. I felt enormous pain in both my legs; they were bruised and grazed," the 77-year-old former home secretary and health secretary wrote in the Sun on Sunday.

London Underground said it was "extremely sorry" that Lord Blunkett was injured and will be meeting with him to ensure that lessons are learned from the incident.

Lord Blunkett, who served as the MP for Sheffield Brightside and Hillsborough between 1987 and 2015, said: "As I took a step to get on to the Tube train I suddenly felt both my feet disappearing down the gap.  In an instant my body had been propelled forward into the carriage and I was face down on the floor.  My legs had somehow been scraped out of the gap and into the carriage."

The fall comes after Lord Blunkett had a recent heart attack which means he must take blood thinners - making any bruising or bleeding more dangerous.  He explained that an X-ray confirmed "extraordinary bruising", but no broken leg, and he was "angry" about what had happened.

Lord Blunkett said: "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, you cannot see."

He is calling for TfL to fill the widest gaps on platforms and make sure there is always someone there to help, especially during rush hour.  He added "some of our platforms are death traps. The gap between the walkway and train is huge and they are unsafe for everyone, but particularly for blind people."

Lord Blunkett is expected to request TfL launch an urgent review into the safety of the busiest tube stations.

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."