As a former trade union officer and now a member of Unison London region's Labour Link committee, it's clear to me that there's only one choice for our Mayoral candidate: Tessa Jowell.
To start in the obvious place, Tessa is a lifelong friend of trade unions and their members. As Olympics minister she ensured a progressive partnership with building unions so that their members weren't exploited as they were helping to build a great legacy for London.
After 7/7, as minister for London, it was Tessa who assembled representatives of the capital's emergency service workers to thank them for their bravery and professionalism in responding to that tragic day.
And this goes back further still. When Major's government had a crazy plan to break up the London Ambulance Service, it was Tessa who acted as a vocal critic from the Health Select Committee and helped the unions make their case successfully in Parliament.
Frankly, Tessa has always been there for unions and their members. But she's won my support - and that of hundreds of trade unionists from former General Secretaries to grassroots members - for much more than that.
Tessa understands the needs of the millions of working people for whom living in London is becoming more and more of a challenge, and wants to do something about it.
Whether trade union members or not (and if only more were, particularly those working in the private sector, most at risk from exploitative employers), working people across London want to do more than just get by, they want to be part of a booming city; and make sure their children can make the most of their potential.
Tessa's plan to create 'Homes for Londoners' shows a clear, precise blueprint to build social and affordable homes - including innovative 'rent to buy' homes - in the numbers necessary to allow people on ordinary wages to live in the capital.
She campaigns on the issues that don't always lead the news bulletins but make a real difference to Londoners' lives - from her innovative action to end the transfer tax to her petition to create a pan-London register to drive out those rogue landlords who provide sub-standard, unsafe accommodation.
And her clear vision to use Olympic legacy funding to prioritise Sure Start in London will provide a win-win for London's millions of working parents. She understands the importance of the first 1,000 days of a child's life in establishing their chances for the future.
My daughter starts school in September - she'll be ready to make the most of her time at school, but four out of ten of her peers across the capital won't be as well placed because they are born into poverty. The odds are stacked against some London children from birth. We need a Mayor anxious to take action on this.
Good quality affordable childcare doesn't just benefit children - it allows parents to get jobs and work more hours, creating a virtuous circle which breaks the generational long-term unemployment blighting too many London households.
From tackling low fares to boosting apprenticeships, Tessa has developed a programme which addresses the agenda of trade unionists: on jobs, skills, housing and transport. She is ready to shake up City Hall and make the most of her time in office (a stark contrast to the part-time Mayor we currently have, serving out his time with a whimper, not a bang).
But all the good policies in the world won't make a difference to trade unionists - indeed, any Londoners - without a Labour Mayor.
The final, compelling reason to back Tessa is that she can win - and deliver change for working people. I'm pleased she's rejected any London equivalent of a '35% strategy', capping our ambition in an attempt to assemble building blocks of support.
Her ambition is as bold as her vision, reaching out for votes across London, from zone one to six. At a time when Labour is crying out for strong leadership, she is a natural leader, attracting support from all quarters and all voters.
How badly we need the politician with biggest personal mandate in the country to be Labour. With Tessa we can win, we can win big, and we can create her vision of 'One London', providing real hope and a bright future for all Londoners.
To join Trade Unionists for Tessa, email firstname.lastname@example.org