He told The Grocer: "Three years after the creation of United, our results show that mergers between strong societies can deliver improved service and advances in financial performance."
Marks delivered another rally call for consolidation as United's pre-tax profit rose 17.1% to £56m on sales up 10.9% to £2.09bn, driven by a 14.4% increase in Food Group sales to £920m.
C-stores, 90% of United's Food Group portfolio, delivered a 10.2% rise in like-for-like sales.
United said its food store refurbishment programme had been highly productive, generating sales rises of up to 41% in certain locations.
Food Group general manager Tim Hurrell said: "Growth by acquisitions, improving store standards and availability and increasing our fresh foods range have all helped drive up sales."
Marks said the society would double its acquisition budget to £200m this year, focusing on food and pharmacy.
United was forged three years ago by the merger of the United Norwest and Yorkshire societies.