Cagatay - apologies for falsely presuming you haven't looked at the FAQ: the preceding exchange in this thread seemed to be of basic nature to me.
Formally speaking, you are right, there are no explicit restrictions on the kind of work you do. However, the HSMP programme indicates that a successful applicant is expected to work in the chosen field. Questions 40-44 on the FLR(IED) form are meant only for HSMP applicants for extension and seem to point specifically at the aspect of one's occupation. Therefore, it seemed safe to assume that HO may very well not extend the stay for those who declared themselves highly skilled in one profession, but are active in another.
At the same time, HSMP is an open programme (besides being recent and thus still evolving). It is entirely possible that HO case workers may execise individual discretion and extend someone's stay despite the difference in occupation, especially in those cases where it's somehow related to the stated one. It is also possible that case workers may grant extensions to anyone who shows good activity or is otherwise 'promising'.
It's just not something to count on - at least not yet - that one will surely get an extension, as long as one is making a living in the UK.
Hope this helps and good luck!
