Crossword

Each of twelve clues comprises a definition part and a hidden consecutive jumble of the answer’s letters including one extra letter; the extras spell the name (two words) of an organisation celebrating a significant anniversary of its 1A (unclued) this December. One clue is without a definition; its answer is the surname of the 26 (unclued) who was the 1D 13D (unclued) of the organisation. Each of six clues consists of definitions of two words of different lengths; in each case, thematically relevant letters are added to the shorter word to create the longer one, which is the answer to go in the grid. Numbers in brackets refer to lengths of entries.

Across

5 Advanced instrument for

capturing images (6) 9 Appeal in retreat endlessly

repeated (7) 10 Copper praises safety

devices (3-4) 11 Honours rarest ethical

values (9) 12 Poisonous snake round loaf

of bread (5) 13 Old man one deployed in

airborne force (4) 14 Lizard with cool name

endangered (9) 16 Lecture society about arcane

matters (9) 18 Mark made by singular

vehicle (4) 21 Publication surprises author (5) 22 Sealed alliance, having

Mexican dish (9) 25 Choose name of mythological

princess (7) 27 Scrap metal’s suitable (6) 28 Ground only covered by

revolutionaries (8)

Down

2 Obscure relative supported

by a king (7) 3 Hate editor coming up

with experiment (6) 4 Lowest point found in crater (5) 6 Items for sale at cinema (8) 7 Cool as in river going north (7) 8 Sailor in tears resolved to be

teetotaller (9) 10 Purgative character in

conspiracy of senators (7) 14 Accord, dream unlikely to be

fulfilled (7) 15 Base exercises on quantity seen

around street (8) 17 Famished, so try sizeable

shellfish (7) 19 Explorers locate area of

shore (7) 20 Rabbi’s moving dream (6) 23 Manage to protect southern

wood (5) 24 Advice, say, regarding areas of

land (5)