John runs a van-hire business that consists of 12 ordinary vans of the same type and one extra-large van. On Friday, John contracts with 12 customers, including Basil, for the hire of his vans for the following week.

He also contracts with Tony to hire out the extra-large van for the following week. During the weekend there is a fire at John's premises which destroys six of the 12 ordinary vans and also writes off the extra-large van.

On Monday, John decides to let out the six remaining ordinary vans to the first six of the 12 contractors who arrive at his premises. Basil is the seventh to arrive and, on discovering that there is no van, threatens to sue John for breach of contract. Tony also threatens to sue when he discovers that there is no longer a large van.

Advise John of his legal position.