The planned opening of the East London Line has been cancelled, following unforeseen technical problems and a bitter political row.
Boris Johnson had been due to open a "preview" section of the line at Dalston Junction station tomorrow morning.
However, the event spurred a long behind the scenes row between the Mayor and his opponents, who claimed his appearance would break election rules.
According to City Hall guidance:
"where a particular initiative, proposal, consultation or publication in the period could reasonably be regarded as giving a candidate or their supporters/political party an advantage in the election. In that case, then the initiative should be deferred until after the election...“All GLA generated or funded publicity must be, and must be seen to be, politically neutral. Anything that could reasonably be regarded as giving a political candidate or their supporters/party an advantage in the election is not politically neutral. This applies no matter what the justifications for the publicity are."
Aware of the controversy, TfL had invited some opposition members to the event earlier this week.
However, these invites only went out in the last few days, and some opposition members believed the event would still have breached the code.
A spokesman for the Mayor insisted that the event had been cancelled due to problems in attaining the proper certification, and not because of the ongoing row.
However, the leader of the Labour group on the Assembly Len Duvall said today:
"Boris Johnson is in chaos over his stunt to hold an official event using taxpayers' resources during an election campaign. He's been trying to take credit for a project delivered with £1bn of investment under a Labour government and a Labour mayor, but his party still won't commit to complete the next step that London needs - the Crossrail link."
Labour have seized on what they believe is the lukewarm support given to Crossrail in the Conservative manifesto.
The Tories have pledged to "support" the project but have not specified whether it will be completed in it's entirety.
The East London Line will open in full after the general election next month.
No new dates have yet been set for the opening of the first section.
-Update- Boris will press ahead with the event, now expected to happen next week. A senior TfL source told me last night:
"It's not going ahead tomorrow as the line isn't ready, but it will, we hope go ahead when it is. We need the line open as soon as it is ready. We want the revenue and the experience of people using it, and we want the exposure the Mayor will get us by opening it."
A spokesman for the Mayor said:
"Under the pre-election guidance the GLA and TfL are expected to conduct business as usual. This is the long-awaited opening of a railway that will benefit 100,000 Londoners daily and certain publicity is required to make the trial of the new services effective. The Guidance provides that it is appropriate to mark this opening with a non-political event. Members of all the main political parties on the London Assembly have been invited as has the Chair of the Assembly Transport Committee."
The argument from the Mayor's side is that that publicising the new line is far more important than any political considerations.
Will it satisfy his opponents?