Yes, an employment contract can be verbal. However, it can often be difficult to prove what was agreed verbally and there is more scope for one of the parties to challenge what was said. Verbal agreements can certainly be contractual and employers need to be careful that line managers don’t inadvertently make contractual offers which become binding.
It is also possible for clauses to be implied into a contract through custom and practice, incorporated through a staff handbook or a collective agreement, included through negotiation with the unions or added as a result of a piece of legislation.
Although an employment contract doesn’t have to be in writing, employees and workers do have a right under s.1 Employment Rights 1996 to be given certain information in writing from day one of their employment. This is known as a “written statement of employment particulars”. It is not an employment contract but most employers do use it as the base for their employment contract as it covers the key terms you would want to include in an employment contract.