LONDON, 31 August 2003 — Alastair Campbell’s departure from Downing Street is timed to coincide with that of his partner Fiona Millar and signals the break-up of the most important foursome in British politics.

While Campbell battled at home and abroad at Blair’s side, Millar offered invaluable advice as Cherie Blair’s personal assistant and gatekeeper at Number 10.

The “his-and-hers” combination worked well for years, the tightly knit unit created a confidentiality at the top of New Labour that only close couples can achieve.

Both in Opposition and Government, Millar was the perfect support to Mrs Blair as she attempted to balance her role as a mother, high-flying QC and party leader’s wife. Their two families looked extremely similar. Young, high-achieving, politically astute, each with three children (until Leo arrived) and living in cosmopolitan north London, the Blairs and Campbells had so much in common that it was no surprise that they gelled so well.

Millar began working for Mrs Blair in 1995. Once Labour came to power, she acted part-time as an adviser until taking on the role full time in 1998.

Formally speaking, Millar was “head of events” at Downing Street, but she was effectively in charge of Cherie Blair’s public life. She would organise Cherie’s forays into charity work, speeches, regular teas with children at Number 10 and consort’s role alongside the Prime Minister on official trips abroad.

However, the couples have never been on holiday together and have not always seen eye to eye, the most notable incident in Opposition being the Blairs’ decision to send Euan to the selective Oratory school.

Both Campbell and Millar are passionate believers in state education, with the latter a governor at two schools and all three of their children attending local schools. Earlier this year, Millar went public with her worries about the school funding crisis that threatened to cut teaching posts at Gospel Oak primary school.

But the biggest crisis in the relationship came during so-called Cheriegate, when Mrs Blair’s “lifestyle guru” Carole Caplin caused headaches for Downing Street through her then boyfriend, convicted fraudster Peter Foster. When it was revealed that Foster had helped the Blairs buy two flats in Bristol, Number 10 at first denied that there was any connection between him and Cherie until emails sent between the two revealed a much closer association.

Even before Cheriegate, Millar and Caplin are said to have fallen out spectacularly over the hold the latter had over Cherie. Campbell also has little time for Caplin, who is credited with teaching Cherie Blair ‘how to dress’ when she moved into No 10.

But Millar has insisted to friends that Caplin is not the reason she is leaving. She first thought about resigning after the last election in 2001, but delayed after Anji Hunter’s departure as Blair’s gatekeeper.

Millar has told colleagues that it is time to improve her “work-life” balance, insisting she doesn’t want to stay in Number 10 “until I retire”.

A former journalist who met Campbell on the Mirror trainee scheme, she plans to resurrect her career in the media as well as work for educational foundations. Whatever she does, Downing Street’s most effective mixed doubles partnership will be over for good.