Whether his hopes will be borne out at Gateshead this weekend, remains to be seen. "You can never guess what issues will suddenly blow up at conference," a veteran attender said.
The union has made this year's event a politician-free zone: as its invitations to ministers have been snubbed for the past two years, it did not even ask Ruth Kelly, the Education Secretary.
But Mr Sinnott will want delegates to be on their best behaviour if he is to realise the "adult" relationship Ms Kelly has requested since the union's banishment after failing to sign the workforce agreement.
His members will be aiming to shore up the NUT's opposition to the deal.
Motions include calls for strikes to get a better deal for support staff.
But they will make it clear that support staff should not take whole classes, and there will be calls for teachers to boycott preparing work for cover supervisors and a national one-day strike to secure more funding for teacher planning, preparation and assessment (PPA) time.
Delegates are also expected to consider a call for industrial action where PPA time is not implemented.
However, the NUT's colleagues in Brighton attending the National Association of Schoolmasters Union of Women Teachers' conference will take a different view.
Its members will call on the national executive to continue "to support the roll-out of the workforce agreement". But they will call for a ballot on industrial action "where NASUWT members are denied the full benefits of the remodelling agreement". So if heads refuse to co-operate, things could get interesting.
The NASUWT will also call for an end to the inclusion of violent and disruptive children and better funding for pupil-referral units. It wants greater powers to exclude and a bigger onus on parents to take responsibility for children's bad behaviour.
The campaign for anonymity for teachers accused of malicious allegations will also continue.
Top of the list of the NASUWT's balloted motions are children's services, extended schools, educational visits and league tables.