Explain how the scope of protection afforded by a patent is to be determined

This is the full topic, as it didnt fit above:

“The question of how the scope of protection afforded by a patent is to be determined, that is, how the position of the boundary fence is to be found, is one of the most difficult in patent law. It is a matter which in the end can only be settled by the court, once it has heard the rival parties’ contentions as to construction of the patent. There are very few cases where the scope is crystal-clear on the face of the patent document itself; it is equally rare for the alleged infringement to be a carbon copy of anything specifically described or illustrated in the patentee’s specification.” (Reid, A Practical Guide to Patent Law (3rd Ed.) p103)

In the light of this statement, and with the support of the principal cases, critically discuss the approach of the courts to patent construction.

I am a UK Law stdent so please only use english ststutes and cases.