This week has been a crash course for Sadiq Khan in the pitfalls of making promises he can't keep.
On Monday he announced that two of the five Night Tube Lines will open in August, with the remaining three lines opening at some point in the Autumn. Rather than take the opportunity to thank the previous Mayor Boris Johnson for all his work to make the Night Tube happen, he decided to try to stick the boot in.
He tried to blame Boris for causing last summer's tube strikes and more than 11 months of delays in negotiation by failing to work properly with the unions.
How timely then when, on Tuesday, the RMT announced that they planned to strike in a dispute over staffing and performance-related pay on the Night Tube.
Given that strikes by the tube unions have already delayed the Night Tube by 11 months we might have expected the new Mayor to have ensured that there were no more planned strikes before making his announcement.
In addition, it is worth noting that on 2nd February Sadiq Khan promised: "As mayor what I'd do is roll up my sleeves and make sure that I'm talking to everyone who runs public transport to make sure there are zero days of strikes."
Promising no tube strikes for the next 4 years was a huge hostage to fortune so I was keen to check whether the Mayor wished to stand by his promise. So this morning, at Mayor's Question Time, I asked him if he wished to withdraw that commitment to Londoners?"
His response was to row back on his previous promise and suggest that "zero strikes" was now just an "aspiration."
A week that seemed to start off so well for Sadiq Khan, has already fallen apart and it's only Wednesday.
Given his swift u-turn on this pledge and others he made during his election campaign, one is left wondering what else the new mayor will fail to deliver for Londoners.