In a move that will delight its 19 million members and mildly irritate everyone else, Nationwide building society this week launched a savings account paying a "market-leading" 5.3% interest. The timing was impeccable: the account debuted just a couple of days before the Bank of England pushed up the main base rate to 4%, a development that savers will greet with the quiet satisfaction of someone who just found an extra fry in the bag.

Nationwide insists the fixed-rate account is part of its commitment to reward existing members for their loyalty - a concept so novel in banking that it may require a moment of stunned silence. The Member Exclusive Bond runs for a 30-month term, and you can pay in anywhere from £1 to £10,000. For those who go all-in with the full £10,000, the interest at the end of the term comes to £1,381 - roughly the cost of a modest holiday, or a very nice sofa, depending on your priorities.

Many experts reckon that 5.3% fixed rate will still look attractive even after Thursday's base rate hike. "Banks have been building an anticipated hike into the rates they offer on fixed-term savings accounts for several months now," said Katie Horne at the savings platform Flagstone. "A single 0.25% base rate increase isn't expected to move fixed rates much further." Translation: the banks already saw this coming, so don't expect a sudden avalanche of even better offers.

At the time of writing, the account puts Nationwide on a par with the top-paying fixed-rate savings accounts over two and three years - a respectable showing for a building society that, unlike some competitors, doesn't require you to sacrifice a goat or download a cryptocurrency wallet to qualify.

The new account can be opened at a branch, online, and via Nationwide's app, which is convenient if you enjoy options. But - and there is always a but - this involves locking away your money for two and a half years. Once the bond is open, you cannot access your cash until the end of the term. For money you might actually need to get your hands on, an instant access account or similar would be more sensible. In other words, don't put your emergency fund in here unless your emergency is willing to wait until 2026.

There are further hoops: you can only pay in money during the first 14 days after opening the account, and it's limited to one per saver. To apply, you must be 16-plus and have had a qualifying Nationwide or Virgin Money account since at least 2 November this year. So if you were hoping to join the party at the last minute, you're out of luck - unless you happen to have a time machine and a previously dormant building society account.