to 2152: T20

Each letter of each solution and each unclued light has to be represented in the grid by its numerical position in the alphabet — the title, T = 20, indicated this transposition. ACROSS: 1 SEVEN 6 Peal 12 Certain 13 SIX 14 Dagger 15 Begorra 16 Vola 20 Bob 22 Betel 23 Kae 24 Dusk 26 Waifs 30 Ria 31 Bevue 34 Lea 36 Black 38 Emures 39 Elchee 40 Bled 41 HUNDRED 42 Dicey 43 Duomi
DOWN: 2 Isabel 3 Wye 4 Elève 5 Regan 6 Joy 7 EIGHT 8 Nahe 9 THOUSAND 10 FOURTEEN 11 Subact 17 Ebb 18 Lob 19 Oracle 21 Edit 25 Salem 27 Ob 28 Ileal 29 Kasha 32 TWO 33 Rode 35 K’ri 37 ONE
 
First prize John Sparrow, Padbury, Bucks
Runners-up Romy Angel, Twickenham; Barry Roe, Leicester