The bid, the highest fee West Ham have ever spent, represents all of Glenn Roeders' current summer transfer budget, but the Hammers boss says it is money well spent.
"To be honest, I never would have sold Rio Ferdinand. Not even for £18m. He is worth far more to the club than that. He's a hard-worker, and a great asset to the team."
What will surprise most fans however, is that Leeds have accepted the bid - £3m less than they paid for him a little over a year ago. The fact is though that Leeds have been crippled by David O'Leary's spending over the past few seasons, and they have to sell in order to stay afloat, let alone buy this summer.
Contributing to their problem is the fact that Leeds look destined to miss the cut for the Champions' League this season, a target that was a must at the beginning of the year.
Rio will be on a large wage at Upton Park, expected to be around £40,000 a week, in a five year contract. But Glenn reckons that the England centre-back is worth every penny.
"I have the full backing of the board on this one, and Rio will come to Upton Park in the summer. The paperwork has gone through without a hitch, and we are well pleased that we managed to keep the deal out of the eyes of the press up until the last minute."
The deal appears to be even better than at first glance, due to the fact that Gary Charles will be heading in the other direction. Apparently O'Leary needs someone approaching Rio's quality to replace him with, and Charles is their man.