✔ 最佳答案
You will able to apply for naturalization as British Citizen after 5 years of legal stay in UK regardless of status. If you are a British National (ie. BN(O), BOTC or BS), you will be able to register as British Citizen after 5 years of legal stay in UK.
http://www.ind.homeoffice.gov.uk/applying/nationality/advice/bn1?view=Standard