National Australia Bank on Friday dropped out, or got kicked out, of the bidding for the 318 branches of Royal Bank of Scotland that are on the market. Reuters reported NAB's exit from the bidding on Friday evening.Most follow up reports over the weekend and today take the approach that NAB's management and board changed their mind, and in effect that the business were not worth buying at the price RBS was seeking.Alternatively RBS, and its adviser, investment bank UBS, let NAB know that its best offer was not good enough. Santander, a Spanish bank that already owns Abbey National in Britain, seems the likely buyer of the RBS branches.NAB may have clarified its options in respect of its current banking business in Britain trading through Clydesdale Bank and Yorkshire Bank.The Sunday Times reported that BBVA, another Spanish bank, is considering a takeover bid for NAB's banks in Britain.Alternative versions of this theory reported over the last couple of weeks are that NAB and BBVA will form a banking joint venture in Britain. One concept is that this joint venture may pursue the two other portfolios of banking branches coming on the market over the next year being sold by Lloyds and also Northern Rock.There has also been talk, which may no longer be current, of NAB listing its banks on the London Stock Exchange.