A third party may concern himself with the doctrine of ultra vires when dealing with the company as any such contracts will be considered void and unenforceable.
It is imperative that third parties examine the contents of the memorandum of association.
Third parties must be aware of the contents of the memorandum.
Any transaction outside the objects clause will be ultra vires the company.
Such a contract is void and cannot be ratified and nothing can be done to render it intra vires.