Sharron runs a hair dresser business. A year ago, she took on Allen as an apprentice and paid him an apprentice salary. Allen had just graduated, he is polite to customers and is committed to doing his job well. While Sharron allowed Allen to work on her customers, such as hair washes, trims and basic cuts, Sharron always checked everything carefully. A few local hair dressers were looking to employ Allen, and offer him better pay. Sharron told Allen that if he stayed with her, she would let him take over the business and share the profits with him. Allen decided to keep working with Sharron, despite knowing that other hairdressing opportunities were available to him.

A year later, Sharron retired. In the meantime, one of Sharron's customer's sons Dimetri, who had been working as a hairdresser at another salon, expressed interest in taking over Sharron's salon. Sharron decided to hand over the business to Dimetri, largely because he was older, more experienced, and was also very popular in town. Allen was disappointed as he thought the business would be his. He confronted Sharron about her promise, but Sharron simply brushed him off and said Allen did not provide any consideration for the promise.

Advise Allen whether he can enforce the promise made by Sharron.

Please use case law to support your answer.