If there is no intention to create legalrelations present, there is no legally binding contract.
Where the agreement is in a domestic or social situation, there is a presumption that there is no intention to create legal relations (Balfour v Balfour).
This can be rebutted (Merrit v Merrit).
Where money has changed hands (even in social situations), it is likley to be deemed a business agreement (Pays).
Where the agreement is made in a business situation, there is an assumption the contract was intented to be legally binding (Edwards).
This assumption can be rebutted, e.g. by including words that this was not the intention (Jones).
Letters of comfort are not usually intended to be legally binding (Malaysian Mining).
Competitions/prizes designed to promote a company confer intention to create legal relations (McGowan).