1. A rule based computerised method of developing and/or rule based systems such as legislation, policy, or other rule sets, the method comprising the steps of: developing a computerised database containing a set of rules in accordance with which the rule based system can be developed, written in and delivered; wherein the rules are:— written in natural spoken language to express the individual grammatical units constituting the rules, constrained in being written in accordance with defined constraints to limit the number of logical formats in which the rules can be expressed, and explicit in being written in a manner to avoid implicit meanings; whereby the rules are expressed in a logical format readily understandable to both humans and computers.