http://www.ukba.homeoffice.gov.uk/polic ... appendixj/
This link is for Appendix J which is to define your business and trading activity according to immigration rules. Once searching out your category and related level (Which should be equal or above than level 4) search your category and related qualifications and job title from SOC 2010 Vol 1 and SOC 2010 Vol 2.
This the way to workout on your role.
Qualification level 7 and Shortage occupation list has nothing to do with Tier 1 Ent. Visa for PSWs. Even HO donot stress on Qualification type and Business category to be same. All they have some magical 'Genuine Entrepreneur Test' which maybe interprets like 'What They Understand, They Do'. This test sometimes convert grey areas of application to white and unfortunately white areas of application to grey. Hope you get it.