Hi Sue,

I'm not sure if it's the same thing, but the General Records Office Index lists the volume number and page number next to the entry, and if you quote this 'GRO reference' when you order on-line from them it's cheaper than ordering without a reference.

Through Ancestry I found the following marriage:

Thomas Cleator (and Elizabeth Skillicorn)
Jun Quarter 1850 Supt. Registrar’s District: Liverpool Volume: 20 Page: 367

You can get access to the GRO and their on-line ordering service at:-

http://www.gro.gov.uk/gro/content/certificates/

"GRO Reference Supplied Full Certificate of birth marriage and death (standard service): £7.00 each"