This crossword No. 12099 clues and answers were published on Wed 18 Feb 2009 and the puzzle can be visited by following The Guardian Quick Crossword No. 12099 link.
All Across Clues and Answers:
1-across – Modest : DEMURE
4-across – Line on map connecting places of equal atmospheric pressure : ISOBAR
9-across – Abrupt in manner : BRUSQUE
10-across – Effective : VALID
11-across – In that place : THERE
12-across – Slaughter : CARNAGE
13-across – Serpent with noisy tail : RATTLESNAKE
18-across – Burial mound : TUMULUS
20-across – Indian prince : RAJAH
22-across – Peer : EQUAL
23-across – Instance : EXAMPLE
24-across – Substance used for misty stage effects : DRYICE
25-across – Attractive piece of metal : MAGNET
All Down Clues and Answers:
1-down – Discussion : DEBATE
2-down – Small rodent — computer attachment : MOUSE
3-down – Ask for : REQUEST
5-down – Break off : SEVER
6-down – Defensive wall : BULWARK
7-down – Long narrow stretch of water between Africa and Arabia : REDSEA
8-down – Favoured pupil : TEACHERSPET
14-down – Weapon store : ARMOURY
15-down – Blissful Buddhist state : NIRVANA
16-down – Be present at : ATTEND
17-down – Menacing words : THREAT
19-down – Light purple — flowering tree : LILAC
21-down – Far Eastern island country : JAPAN
This crossword has in total 26 where 13 are across and 13 are down.