For a brief moment at Monday night's City Council meeting, one of the strangest political alliances in Cambridge history seemed to coalesce.

In a surprise announcement, Mayor Alfred E. Vellucci told the council that he had discussed ways to improve the city's rent control system with Michael H. Turk and William S. Noble of the Cambridge Tenants Union. Vellucci indicated the two would support a means test--which would link tenants' eligibility for rent control to their income.

Such a proposal has long been a pet idea of Councillor William H. Walsh, a vocal critic of the city's current rent-control system who has often drawn criticism from Turk for his close ties to the real estate industry.

Walsh said he was delighted that Turk had come around, but, alas, the Turk-Walsh alliance was not to be. In response to Walsh's comments, Turk told the council that Vellucci had misstated his group's position.

"The Cambridge Tenants Union is opposed to a means test," Turk said.

Maybe Next Week

Monday's meeting also saw what appeared to be a slightly more probable but equally short-lived alliance involving Walsh.

Councillor Alice K. Wolf moved that the council consider on the unfinished business calendar a zoning change sponsored by Susan Yanow of the Cambridge Citizens for Liveable Neighborhoods.

The proposal would limit development by requiring that all new buildings be stepped back from residential zones at a 45-degree angle. Such changes normally require six council votes, or seven if 20 percent of the property owners in the affected area file objections.

After the motion, City Clerk Joseph E. Connarton informed the council that Harvard--the largest property owner in the city--had objected, but that he had not yet determined if a seventh vote was necessary.

Most contoversial zoning changes in Cambridge cannot find even a sixth vote on the council, which is split on most issues between the four anti-development, CCA-backed councillors and four of the Independents.

The mayor, an Independent who often provides the swing vote on zoning changes, reminded Wolf of the political situation and suggested that she be absolutely sure of the sixth vote before proceeding.

But when Yanow told the council that she had received commitments of support from six councillors, Independent Councillor Thomas W. Danehy immediately replied that he had not spoken with her. He then proceeded to question his Independent colleagues.

Councillor Sheila T. Russell said she had not spoken with Yanow. Likewise Councillor Walter J. Sullivan. That left Walsh, a frequent champion of new development.

Walsh told the council that he had spoken with Yanow, but that he was waiting for a reply to a letter he had sent to the community development department before making up his mind on the petition.

To give Walsh some time to get his information, Wolf asked to postpone the vote.