That bodies corporate can be guilty of the offences just as easily as
individuals can
I'm not quite sure what you mean by "just as easily", but in general, corporate bodies can be guilty of offences which individuals can be guilty of. This is because of Section 5 and Schedule 1 of the Intepretation Act 1978:
- In any Act, unless the contrary intention appears, words and expressions listed in Schedule 1 to this Act are to be construed
according to that Schedule.
“Person” includes a body of persons corporate or unincorporate.
Note the phrase "unless the contrary intention appears". Some offences will clearly only apply to an individual e.g. those that talk about intent, or being over 18 years old, or other language that excludes the possibility of corporate bodies.
That the culpability must generally be an either/or affair [...] otherwise, what is the purpose of such clauses as one finds in s. 1(6) as quoted?
This really depends on the wording of the specific offence. Consider for example the offence under Section 72(1) of the Housing Act 2004:
A person commits an offence if he is a person having control of or
managing an HMO which is required to be licensed under this Part (see
section 61(1)) but is not so licensed.
This is subject to the definitions of "person having control" and "person managing" at Section 263 which, in simple terms, means the person receiving the rent and/or entitled to receive the rent and includes agents receiving rent on behalf of another person.
The offence can apply to either a corporation or an individual or both at the same time depending on who is receiving rent or acting as an agent for the other:
Example 1: A corporation handles repairs and administration tasks for a property, not including rent collection, on behalf of an individual landlord who is ultimately entitled to the rent. Only the individual landlord can commit the offence.
Example 2: A corporation manages a property, including collecting rent, on behalf of an individual landlord who is ultimately entitled to the rent. The corporation collects the rent by sending its director to collect cash from the tenant and deposit it into the corporation's bank account. The corporation, the corporation's director, and the individual landlord can commit the offence.
Example 3: A corporation manages its own property, including rent collection directly into its own bank account from the tenant. The directors aren't involved in rent collection but are neglectful in relation to obtaining an HMO licence. Only the corporation, but (in the absence of any further statutory provision) not its individual directors, can commit the offence.
However, example 3 is modified by Section 251(1):
Where an offence under this Act committed by a body corporate is
proved to have been committed with the consent or connivance of, or to
be attributable to any neglect on the part of — (a) a director,
manager, secretary or other similar officer of the body corporate, or
(b) a person purporting to act in such a capacity, he as well as the
body corporate commits the offence and is liable to be proceeded
against and punished accordingly.
The effect of this is to bring the directors within the scope of the offence in example 3 in cases which involve consent, connivance, or neglect.
This is quite different to example 2 in which the director can also commit the offence. In example 2, the director commits the offence directly by carrying out the illegal action (controlling/managing a property without a licence) and there is no need to trigger Section 251. In example 3, the director does not carry out the illegal action but commits the offence indirectly by triggering Section 251.
So to answer your question, the purpose of such a provision is to ensure that directors etc. can be liable for offences committed by corporations in scenarios where they aren't otherwise directly caught by the wording of the offence.