Philip wants to sell his house. He advertises it in the local newspaper. House sale at £370,000, giving his telephone number Jim sees the advertisement and rings Philip and makes an appointment to see...

Philip wants to sell his house. He advertises it in the local newspaper. House sale at £370,000, giving his telephone number Jim sees the advertisement and rings Philip and makes an appointment to see the house. Jim likes the house but cannot agree a price with Philip, his highest offer being £367,000, while Philip insists on £370,000.
On the following Monday Jim receives a letter from Philip offering him the house for £368,500 and saying that Jim can have until noon on Friday to think about it.

On Wednesday evening Jim meets his brother Garrett in a restaurant. Garrett tells him that Philip's son-in-law bought the house earlier that day for £367,000. Jim goes straight home and writes a letter to Philip, accepting his offer to sell at £368,500. He posts the letter immediately and Philip receives it on Thursday morning, but replies by return saying
"You are too late. I have sold the house to my son-in-law."

Advise Jim what step he should take. Give your answer with supported cases.