Suresh
there is slight concern. your deputation letter will certainly help BUT if you were paid in India it won't show you were 'economically' active for UK. In no way i am suggesting it will hamper your application but would have nullied all your concerns if you would have been paid under UK payroll.
My personal thought is in ILR/SET(O) form show your UK period right from when you first entered, before you exited on 19-Apr-10. (this might allow you to go for ILR right now?)
even if you show 19-Apr-10, that allows you to apply for ILR as on 22-Mar-15 (28 days minus 19-Apr-15). Go for same day decision because in case of problem you can go for tier-1(G) extension before 05-Apr-15 when extn closes.
It 's all about clarity from your side as well Case worker to be able to get it to conform to guidelines.
PS: i can discuss offline if you wish? but i am just a novice
Edit: tried PM you but it is stuck in my outbox?