I agree with most replies here, which finds a written business agreement the better option in a project, compared to the verbal agreement, as it and can be easily defended in court and would provide more certainty by stating the details clearly. Depending on someones words and honesty would not always work and could cause some later issues which can be avoided if there were a written statement. Here are some benefits for the written agreements found on Pendragon website:
“A written contract can:
• provide proof of what was agreed between you and the hirer
• help to prevent misunderstandings or disputes by making the agreement clear from the outset
• give you security and peace of mind by knowing you have work, for how long and what you will be paid
• clarify your status as an independent contractor by stating that the contract is a ‘services contract’ and not an ’employment contract’. This will not override a ‘sham’ contract, but a court will take the statement into account if there is any uncertainty about the nature of the relationship
• reduce the risk of a dispute by detailing payments, timeframes and work to be performed under the contract
• set out how a dispute over payments or performance will be resolved
• set out how the contract can be varied
• serve as a record of what was agreed
• specify how either party can end the contract before the work is completed.”

The benefits of a written contract