HSMP Approval with Tier1 LTR 4.5 yrs : am I eligible to ILR

[OS1919]

Dear Friends,

I would like to discuss my possibilities of applying for ILR under 4years stay criteria with yourselves.

My case details are as following :
1. HSMP Application applied on 29th Feb 2008
2. HSMP Approval Letter issues on : 08th May 2008
3. Entry Clearance applied on 23rd July 2008
4. Entry Clearance Granted as Tier 1 General under HSMP Transitional Arrangement on 29th Aug 20008
5. First Entry to UK on : 18th February 2009

Since then I have taken one extension which is expiring on 26th Sept 2013. I have never crossed 180 day holiday criteria for any year.

My query is, since my Immigration Application was HSMP based and later converted to Tier1 General Migrant category for entry clearance, basis that will I be eligible for ILR in 4years of my first entry to country or do I need to complete 5 years?

Kindly let me know if this is the case which we can put across for 4 years requirement.

My visa is due for renewal this month on 26th Sept 2013.

I am ready with all the documents for renewal purposes anyways, but if there is any clause making me eligible for 4 years criteria and let me apply for ILR this time instead of extension.

Friends, Urgent help and advise requested.