The iPhone 5 became Britain's most popular smartphone in March, six months after it went on sale in September.
Apple's success comes as the Samsung Galaxy S3 dropped to third place while fans of the South Korean company wait for the latest model to hit the shelves, according to uSwitch.com.
The S3 had been the UK's number one handset for 10 months but lost its top spot after the S4 handset was unveiled on March 14.
But the popular Galaxy range still dominates the chart, with four places in the top 10, according to the uSwitch.com Mobile Tracker, which is based on searches, pre-orders and sales through the website.
The company said more than four times as many iPhone 5 handsets as S3 phones were sold through their website.
Apple takes a further three places, with the iPhone 4s climbing five spots to second most popular handset in March.
Initial interest for the Sony Xperia Z, which entered the chart at number two in February, waned last month as the phone slipped two places.
March's new entry, the HTC One, which doubles as a remote control and only went on sale last month, immediately became the fifth most popular smartphone.
Ernest Doku, telecoms expert at uSwitch.com, said: "It's not just early adopters that are holding out for the Samsung Galaxy S4 to hit the shelves.
"Since the Korean manufacturer's new flagship device was announced in mid-March, the S3's popularity has already faded enough for not one but two iPhones to get ahead.
"That's a big deal for the smartphone that has managed to spend 10 long months at the top of the smartphone table.
"Although it's still Apple versus Samsung at the top of the chart, there is plenty of mid-table contention between flagship efforts of other manufacturers, including Sony, HTC and LG."
Mr Doku said the most popular phones will likely change again soon, as BlackBerry are hoping to attract sales with their Q10 model and Samsung will introduce new competition with their heavily hyped Galaxy S4.
According to uSwitch.com, the top 10 handsets for March are:
1. Apple iPhone 5 (16GB) (Up two)
2. Apple iPhone 4S (16GB) (Up five)
3. Samsung Galaxy S3 (16GB) (Down two)
4. Sony XPERIA Z (Down two)
5. HTC One (New entry)
6. Apple iPhone 4 (8GB) (Re-entry)
7. Samsung Galaxy S2 (Up two)
8. Samsung Galaxy Note 2 (Up two)
9 .Samsung Galaxy S3 Mini (Re-entry)
10. LG Nexus 4 (Down two)