LSE English Language Requirement

jaina2016

I have achieved a grade 8 in Pearson/Edexcel IGCSE English Language B. On the LSE website it says that this qualification is only valid if I have 5 years education in english.

I am confused on how the 5 years are determined. Is it 5 years from the point before I obtained the qualification or 5 years in general (which will include A - levels)? Also I am unsure of how I am actually meant to prove this. Really not sure what to do, need some help urgently