The other was running the successful campaign for another old school mate, Peter Bevan, who was elected to the Hawke's Bay Regional Council in October. Mr Bevan campaigned on a pro-amalgamation ticket.
Mr Williams took part in his first political campaign in Hawke's Bay in 1978 when another Karamu old boy, David Butcher, was elected as MP for Hasting. Mr Butcher went on to become a Labour cabinet minister.
Mr Williams said he supported the Electoral Commission's proposal to merge Hawke's Bay's five local authorities into a single region-wide council because he believed the region had been going backwards since the 1980s.
"I see amalgamation as a way of arresting that decline. I don't think it's a silver bullet but it's certainly worked in Auckland and I think if Hawke's Bay speaks with one voice they're likely to do a lot better."
Mr Williams is a director of Auckland Transport, the super city's largest council controlled organisation with a budget of over $1 billion.
"The savings we're getting through economies of scale in things like road maintenance and footpath maintenance - they're very much worth having."
He said another example of the effectiveness of amalgamation in Auckland was the major government investment being made in upgrading the city's rail network, including plans for a city rail loop.
Mr Williams' pro-amalgamation stance puts him at odds with former Labour Party colleague Stuart Nash who has been running a high-profile anti-amalgamation campaign in Napier.
He said the two men had "agreed to disagree" on the issue during a phone call last week.
The chair of the A Better Hawke's Bay Trust, which put forward the proposal that triggered the Local Government Commission's amalgamation plan, said the trust was delighted to have someone with Mr Williams experience helping the campaign.
Ian Dick, chairman of anti-amalgamation lobby group Democratic Action Association, said the group would be releasing details of its strategy over the next week. He was not concerned about Mr Williams' involvement with the trust, which he said had a number of "big guns" on its side.
With the amalgamation debate destined to be decided through a referendum late next year, Mr Williams said a key element of the campaign would be encouraging voter turn-out.
"That to me is just like an election campaign. You've got to put your arguments, do your publicity and motivate your supporters."
While Napier is generally seen as opposed to amalgamation he said he did not believe the city was universally against the plan. A major concern over Hastings' debt had been addressed by the commission's proposal to ring-fence it.
The commission's proposal that Napier become the headquarters of the amalgamated council should also ease concerns, he said.
"In that case Napier goes from being any other provincial city in New Zealand to a regional capital. I think that's a huge advantage."