entry clearance reference nmber

[Visa_Novice]

Hi,

I have a work permit and applying for tier-1 in-country.
What will be the reference number for the following requirement on page 17 of tier-1 application:

D4. Please enter the reference number on the entry clearance or visa which can be found in the applicant's passport or travel document.

Now I have following kind of reference numbers. Kindly advice which one I should use :
1. Our reference : XXX/XXXXXXX/XXX - Written in work permit document
2. Worker reference number: XXXXXXX - Written in work permit document
3. VAF No: XXXXXXX - Written in passport WP visa stamp
4. There is one more 9 digit number written in Red color at the top right corner of the passport WP visa stamp.

Kindly help.

Thanks.

[destiniation_london]

it would be the one in red on the top right of your first visa