Question on Tier 1 Validity

I had Tier 1 visa granted in Sep 2008 valid until Sep 2011. However, I did not travel on it due to some commitments.

I got another Business Visa issued to UK in Aug 2010 for six months, and I travelled on it for 4 days. I did not use Tier 1 then, though it was valid as the purpose was not for employment.

Questions:

1) Is Tier 1 leave invalidated as the business visa was granted and used?
2) Can I appy for Tier 1 entry clearance again, irrespective of the validity of Tier 1 visa granted previously?

Appreciate your opinion / advice.

Regards

1. Yes.
2. Yes.


regards