Send both the copy of the lost passport and and the new one. I believe you need to show the passport(or copy or other evidence) by which you initially entered the UK See the guide and the form here.

Pay special attention to the date you send your application...see page 5 of the guide for more information. You must have been physically present exactly three or five years (depending on the which basis you are applying)to the day the HO receive your application. Read the guide thoroughly as there are a few exacting criteria you must meet.

http://www.ind.homeoffice.gov.uk/6353/11406/guideannew.pdf

http://www.ind.homeoffice.gov.uk/6353/11406/annew040806.pdf

When you become a BC then you can apply for a British passport

Thanks very much for your advice and your reply

yes i still have my original passport but it has expired, the one which had ILR stamped on it has been lost

do i have to send the FIR copy as well

I came in july 1999 and was granted ILR in May 2005

shabnam

no i didnt receive any letter from the home office for ILR. they just stamped my passport with ILR.

and since july 1999 i didnt leave  uk until last year when i was granted ILR.

Hi

i passed my test today. thanks for your site it really helped me to prepare for my test.

i need some advice, the thing is i was granted ILR in May 2005. but i lost my passport while i was visiting my parents in Pakistan.

I had to apply for my passport and visa all over again. my passport was stamped with the visa for Returning resident.

now i want to apply for british passport, can somebody advice me what i need to know. do i have to send the photocopy of  lost passport as well or just my new passport

thanks

shabnam