LONDON -- As you may already know, Berkshire Hathaway (NYSE: BRK-A) (NYSE: BRK-B) CEO Warren Buffett has spent more than $1 billion buying the shares of one of the U.K.'s most successful large caps.

Clearly he thinks there are bargains to be had within Britain's elite FTSE 100 (INDEX: ^FTSE) index -- and my research suggests there are plenty more buying opportunities for smart American investors prepared to look across the Atlantic.

So as you wait for the Dow Jones Industrial Average (INDEX: ^DJI) to open this morning, I'd encourage you to consider the American depository receipts of Barclays (NYSE: BCS) for your portfolio.

Big four British banks
Deciding which, if any, of the big four British banks to buy is a tough call. Royal Bank of Scotland is the most deeply contrarian, followed by Lloyds Banking.

Meanwhile, HSBC looks the "best" of the bunch, but it doesn't offer as much bounce-back potential. So perhaps the best investment, on balance, is Barclays.

Barclays didn't go cap-in-hand to the U.K. taxpayer during the financial crisis, unlike RBS and Lloyds, which are effectively still part-nationalized. Instead, the bank was backed by Middle Eastern investors, which included the Abu Dhabi and Qatari royal families.

Also, Barclays' investment bank managed to avoid the huge writedowns taken by many of its peers, which should enable it to gain market share when the wider economy picks up. You may know already that, during the banking crash, Barclays managed to buy the profitable parts of Lehman Brothers at a bargain price.

And unlike RBS and Lloyds, Barclays at least pays some dividends. With the ADRs at $13, the stock is expected to yield a respectable 4.3%, while the projected P/E for 2013 is just 5.4. Furthermore, the $40 billion market cap represents just 53% of the bank's net tangible assets.

Potential upside
There are a lot of people in London who are paid vast sums of money to pore over Barclays and try to decide what the stock's prospects are in the immediate future. The best way for the ordinary investor to fight back against this is to take a wider perspective -- unless, that is, you're truly blessed with a rare ability to trade successfully.

So let's concern ourselves with what Barclays' figures may well look like in 2017. On that front, the overall picture is something of a mixed bag, but most definitely one of a bank heading in the right direction. It's making progress on a "two steps forward, one step back" basis.

Look back not too far in Barclays' history, and historical earnings would place today's $13 stock on a P/E of four, with a dividend yield of around 15%. A few years ago the stock traded at three times its current level -- and for me, that shows the potential upside over the long term.

So all in all, Barclays' ADRs appear very lowly rated, and the company itself looks the most balanced U.K. banking play for patient investors cool enough to ride out any eurozone worries.

Let me round off by adding that this special Motley Fool report -- "8 ADRs Held By Britain's Super Investor" -- reveals the FTSE 100 stocks favored by U.K. investment legend Neil Woodford. You may be attracted to the ADRs of the companies he owns, too. The report is free.

The Motley Fool is helping Britain invest. Better. And with the economy so uncertain, we're urging everyone to read "10 Steps To Making A Million In The Market" -- it may transform your wealth. Click here now to request your free, no-obligation copy.

Further investment opportunities: