On 1st October Sam placed the following advertisement (with a photograph) on Classic Cars, a website for vintage car enthusiasts. 'For sale: 1972 Triumph Herald, 50,000 miles, showroom condition; 4,000 for quick sale.' He includes an email address, mobile telephone number and postal address.

On 2 October at 2.00 pm Betty reads the advertisement and sends a text message to Sam's mobile 'phone ' Can you send more photos. How about 3,600?' She includes her email address. Sam receives this message and reads it on the same day. In response, he sends three photographs by email with a message saying '4,000 is the lowest price. Must hear from you by 4th November.'

On 3 October at 5.00 pm Charles sees the advertisement on the website and sends an email stating 'Please reserve Triumph Herald for me at 4,000. Deposit in the post.' Sam is not on-line at the time, but his computer's server sends an automated message in his name: 'Thank you for this message. Sam will reply as soon as he is able.'

On 4 October at 3.00 pm Betty leaves a message (with her name) on the answer-phone of Sam's mobile telephone '1972 Triumph Herald: agreed at 4,000.'

On 5 October at 9.00 am a cheque for 500 drawn by Charles arrived by post at Sam's address together with a note stating 'with Charles's compliments as per our agreement'. Sam deposits Charles's cheque in his own bank account immediately. At 10.00 am Sam switches on his mobile 'phone and listens to Betty's telephone message.

On 6 October Betty and Charles both send email messages to Sam stating that they are looking forward to collecting their car and ask what arrangements for delivery they should make.

Discuss the contractual consequences, if any.