The pair said they saw "significant industrial logic" in the combination by merging their complementary online and land-based operations and making substantial revenue and cost savings and economies of scale.
They added: "No formal approach has yet been made to the board of William Hill and there can be no certainty that any such approach will be made."
If it happens, the tie-up would be the latest in a string of such moves in the industry.
William said in a separate statement that it received a "highly preliminary" approach from 888 and Rank regarding a potential combination of the three companies.
It said the consortium did not put forward a proposal or set out a position on price, timing, terms, form of consideration or transaction structure.
William Hill said in a statement: "The board of William Hill would listen to and consider any proposal which might be forthcoming from the consortium.
"However, it is not clear that a combination of William Hill with 888 and Rank will enhance William Hill's strategic positioning or add superior value to William Hill's strategy, which is focused on increasing the group's diversification by growing its digital and international businesses."