Consumer Credit Act 1974: Primary legislation governing consumer credit agreements, including requirements for credit agreements, disclosure obligations, and cooling-off periods for consumer transactions.

Late Payment of Commercial Debts (Interest) Act 1998: Legislation governing late payments in commercial transactions, including statutory interest rates and compensation provisions for late payment in business-to-business agreements.

Limitation Act 1980: Sets statutory time limits for enforcing debts and bringing different types of legal claims in England and Wales.

Unfair Contract Terms Act 1977: Regulates unfair terms in contracts, particularly focusing on reasonableness of terms and limitations on exclusion clauses.

Consumer Rights Act 2015: Modern legislation protecting consumer rights, ensuring fairness and transparency in consumer contracts and terms.

Financial Services and Markets Act 2000: Regulatory framework for financial services, relevant if the installment agreement involves regulated financial services.

Common Law Principles: Fundamental legal principles governing contract formation, including consideration, capacity to contract, and intention to create legal relations.