This crossword No. 11304 clues and answers were published on Sat 29 Jul 2006 and the puzzle can be visited by following The Guardian Quick Crossword No. 11304 link.
All Across Clues and Answers:
1-across – Light volcanic rock : PUMICE
4-across – Stand-in doctor, clergyman etc : LOCUM
7-across – See 11 : CORNER
8-across – Substance contained in many grains : GLUTEN
9-across – Discharge from volcano : LAVA
10-across – Canine guard : WATCHDOG
12-across – Documentary evidence of competence : CREDENTIALS
17-across – Undergo spasms : CONVULSE
19-across – Pig fat : LARD
20-across – Refer indirectly : ALLUDE
21-across – Water-cooled tobacco pipe : HOOKAH
22-across – Go in : ENTER
23-across – Smeared blot : SMUDGE
All Down Clues and Answers:
1-down – Unimaginative – air cops : PROSAIC
2-down – Artwork formed from different elements pieced together : MONTAGE
3-down – Sideways somersault : CARTWHEEL
4-down – Light purple – flowering tree : LILAC
5-down – Urban stronghold – dialect : CITADEL
6-down – Cope : MANAGE
11-down – Final bend at Epsom racecourse : TATTENHAM
13-down – Curled lock : RINGLET
14-down – Including everything : ALLTOLD
15-down – Outer layer : SURFACE
16-down – Graze – awkward predicament : SCRAPE
18-down – Mammary gland of cows, sheep etc : UDDER
This crossword has in total 25 where 13 are across and 12 are down.