The iPhone 3G S has gone on sale in the UK today to what appears to have been modest crowds, as stores opened early to accommodate those keen to get their hands on the new Apple handset.

Apple's Regent Street store in central London saw queues start from 3am, slowly building through the dawn until around 40 people were reported to be let into the store for the 8am sales start, according to blogger Richard Lai.

O2's sales appear to be going well with a spokesperson telling Pocket-lint, "We've seen over ten times our average footfall in our stores compared to an average day. We've seen queues outside most of our stores and we are happy with sales".

However, it seems Carphone Warehouse, who racked up 18,000 pre-registrations for the device and opened its stores even earlier from 7am for the launch, may have messed up.

More news is coming in as we write, but reports are suggesting that the retailer has failed to deliver pre-ordered iPhones to some of its stores.

PCAdvisor reports from the Islington branch of Carphone Warehouse that customers who had pre-ordered the iPhone 3G S, and gone through the necessary checks and paperwork, were told delivery delays would mean their handsets would arrive "between 9am and 5pm", rather than the collect-at-7am service they were expecting.

Twitter user FodT reports: "waiting for carphone warehouse to deem me worthy to receive an iphone 3gs. can't have one from stock because 'mine' is in a van somewhere..."

Good_dancer is equally unhappy: "No iPhone for me today. Carphone Warehouse screwed up and let people order what they had already sold out of".

Carphone Warehouse is also under fire from customers for not offering the PAYG version of the iPhone 3G S despite apparently informing customers they would be.

Moviedan says: "Despite Carphone Warehouse allowing a preorder on a payg 3GS, they've now decided they're not selling them and have lost my order. Tossers".

Pocket-lint has contacted Carphone Warehouse for clarification but we're yet to hear back. We will keep you posted with news of this, and the New York iPhone 3G S launch, as we have it.

UPDATE: Carphone Warehouse has been in touch with news of the launch. "It’s proving to be a great day for us with sales of the iPhone 3G S surpassing our expectations", the retailer says.

"All of the customers who ordered their handsets in-store had their orders successfully fulfilled this morning. Those customers who ordered their handsets on-line will, as stipulated in the email confirmations they were sent, have their iPhones delivered to the store of their choice between 9am and 5pm today".