The £800 million ($986 million) pension fund pondered an exit from the pool, which runs pension assets for the 32 London boroughs, earlier this year as it questioned its benefits.
The U.K. government in 2014 required local authority pension funds to pool assets to help them achieve cost savings and diversification through pooling of investments.
But Mr. Marshall said in an email that there is "very little evidence to suggest any such benefits exist."
Still, he said the pool's new CEO, Dean Bowden, who was appointed into the role in November, has brought "a fresh approach to the London CIV, and we hope and expect our future working relationship to be much improved."
In response to the decision by the pension fund to remain in the pool, Mr. Bowden said in an emailed comment: "We are delighted that RBKC will be remaining with London CIV as its chosen pension pool. London CIV is focused on delivering real value through both asset pooling and a broad service offering, to the benefit of our shareholders."
London CIV managed about £12.6 billion ($15.2 billion) in public markets assets and about £2.3 billion in private markets assets as of Dec. 31 on behalf of the London pension funds.
Commenting on the success of U.K. LGPS pooling in the U.K., Iain Campbell, senior investment consultant at U.K. consultant Hymans Robertson, said the pools were set up to provide local authority pension funds with greater scale, lower fees and improved governance of investments.
Mr. Campbell said that management fees have been cut significantly due to the increasing buying power brought by the pooling of assets, particularly private assets. Pooling also allowed funds to get strong input on investment oversight, he added.
But he noted that in order to achieve these benefits, partner funds need to agree on what their joint investment funds should look like.
"This is where there has been scope to be disappointed," he said. "Investment funds in certain asset classes may not be offered if there are not enough partners funds and assets interested, even if that investment is important to a particular partner fund. Partner funds will either need to maintain those assets outside of the pool or disinvest from that asset class."