Don Manley’s equally excellent book The Crossword Guide published by Chambers has these categories
1. Anagrams (Chapter 4)
2. Charades (Chapter 5)
3. Containers and contents
4. Reversals
5. Hidden words (Chapter 6)
6. Vocal clues
7. Subtractive clues

Charade has been and always will be a significant category of clues. Other bloggers may not exactly have used the word “charade” but they do allude to the device.

I happen to think that I should also address my blog to newbies who may not understand such notations as S-WEE-NEY (for 2Down) which only a seasoned and experienced solver can comprehend. Hence my long explanation spelling out the wordplay in detail and pointing out obscure definitions.

I guessed OPUS DEI almost immediately: it’s been in the public eye fairly recently as a result of featuring in “The Da Vinci Code”, and also because Ruth Kelly is a member – a fact that caused some controversy when she was dealing with “faith schools” as Secretary of State for education, as well as speculation as to whether she wears the cilice (barbed-wire underwear, basically).

Remembered from primary school: the legend is that Blondel ‘discovered’ the Lionheart, who had been captured by Duke Leopold of Austria, by travelling Europe from castle to castle, singing a love-song that they had composed together. When he reached the castle where Richard was imprisoned, he heard the king singing the refrain. Subsequently, Richard was ransomed.

5dn – this must be Araucaria’s mistake, although I worked out the clue assuming the postal district of Buckingham Palace was W1.

17dn – KERYGMA was a new word to me (I recognise GUERDON from crosswords!) but it was fairly obvious from the wordplay and had an authentic Greek look to it. Another good example of a relatively easy clue for a relatively difficult word.

Satisfying example of the good Rev’s art; my favourite clue was 19ac, with its allusion to the infamous ‘Yo, Blair!’ greeting by George Dubya.