Complex sentence: Developing from work he did for the Conservative Party in his Deputy Chairman role, since 2010 Lord Ashcroft has been a major independent public pollster of British political opinion, including polling at constituency level, which is rare in British psephology.
Split into simpler sentences: Developing from work he did for the Conservative Party in his Deputy Chairman role, since 2010 Lord Ashcroft has been a major independent public pollster of British political opinion. This has including polling at constituency level, which is rare in British psephology.