Which Date of Arrival?

I have had several different visas/immigration status since I arrived in the UK
1. Ancestry Visa (granted in 2000 and then a repeat ancestry visa when I returned in 2005 - I have lived in the UK permanently since then)
2. Limited Leave to remain (granted in 2009)
3. Indefinite Leave to Remain (granted in 2014)

I am now applying for BC and I am wondering what to put as my "date of arrival"?
Do I state it as 2005 and send in my old old passport from the time as proof of this?

This goes further back than the 5 year period I am using as proof of my residence in the UK (I will need to send in my 2 most current passports to prove this)

So basically I will be sending in 3 passports to prove a) when I arrived and b) that I have been residing here for the last 5 years?

Is that correct and does it make sense?

1. State 2005 - as that was the date from which you stayed.
2. No need to prove this date, don't send the old passport.
3. Only send the passports covering the five year residency period.

based on a recent experience with a family memeber's application, I will advise the OP to also send the passport with which the OP enetered the UK in 2005 if available