SRG1157 is the Examiner's Record. The Guidance material is in Standards Doc 14(A)
http://www.caa.co.uk/docs/33/DOC%2014%20V5%20.pdf
4.4
Examiners may only take the administrative action to renew a rating up to 5 years from the date of expiry of the rating. After that period examiners may not make any entry in the applicant’s licence. The appropriate associated paperwork must be sent to PLD for licence endorsement together with the current fee as per the current scheme of charges.
SRG1157 broadly contains the content, although Appendix 1 to Standards Doc 14(A) specifys the content in more detail plus tolerences.
Of course, following the test you then need to include the CAA fee of £84 to renew the Class Rating if it's over 5 years. If it's less than 5 years the examiner can sign your Certificate in your licence with no administrative fee to the CAA.
Current CAA Scheme of Charges here:
http://www.caa.co.uk/docs/33/241PLS.pdf
No grief either way, just more dosh!