Gazza rates today's puzzle as 4 stars for difficulty and 4 stars for enjoyment. I must say that I did enjoy doing this puzzle. Although, I completed it in a fairly respectable time, I was left with one clue that I really did not comprehend and one where I blundered.
Some possibly unfamiliar abbreviations, people, places, words and expressions used in today's puzzle
Used in Solutions:
mo - noun informal,
OM - abbreviation (in the UK [and Commonwealth realms]) Order of Merit: an honour bestowed by the reigning monarch of the Commonwealth realms upon citizens of those countries
Gazza's review of today's puzzle may be found at Big Dave's Crossword Blog [DT 26153].
After the appearance of American General Ulysses S. Grant yesterday, when I saw yet another U.S. general, not to mention Canadian police officers, in today's puzzle, I was expecting an outcry arising from visitors to Big Dave's site. However, it did not materialize. Perhaps the Brits are becoming inured to the occasional North American reference.
Commentary on Today's Puzzle
12a Old are going to diminish (4)
I needed help from Gazza on this clue. where "old are going to" is equivalent to saying "archaic word meaning are going to", as in the Wiccan Rede, "An it harm none, do what thou wilt".
18a Agent's cover holding gun (6)
Although I saw the wordplay in this clue almost immediately, I was held up for a long time thinking that "cover" must be referring to lid. Eventually, I realized that we actually need a different 3 letter word starting with L - one meaning cover of quite another sort.
20a General accepting medal for regular (8)
We last saw this medal in Monday's puzzle. Not only did this general die more than 25 years before this honour was first bestowed, but being an American, he would not have been eligible for full membership - although he perhaps could have been granted honourary admittance.
1d Howl with pain (4)
My first stab at a solution here caused me some pain. I thought that the solution might be OUCH (a howl one may make when in pain), which definitely slowed me down for some time in the northwest quadrant.
4d Cause and effect (8)
It is generally frowned upon in a double definition for both definitions to have the same meaning. That is, the two parts of the double definition are expected to each be a meaning of the solution without meaning the same thing themselves. Before reading Gazza's review, I thought that this principle might have been violated by this clue. The solution is OCCASION, a verb meaning "cause". The first definition is cause and the second is effect, which can also be a verb meaning "cause to happen; bring about". Thus, it would seem that the two definitions and the solution are all verbs being either cause or a word meaning cause. However, it seems that I have no cause for concern, as cause can also be a noun meaning reason or occasion (in the sense that I have just used it). So, although the reasoning may be a bit convoluted, the two definitions are "cause = reason = occasion" as a noun and "effect = cause = occasion" as a verb.
22d Stretch from detective's overdue (6)
Oops! I made a major blunder here by having the detective as a PI (private investigator). This produced PILATE which I thought might be a singular form related to the exercise system known as Pilates (and which might involve stretching). When I tried to verify my theory, I discovered that Pilates is the surname of Joseph Pilates, the developer of this physical fitness system. That left two choices, either I had the wrong solution or the setter had made an error. At that point, I should have accepted the inevitable, recognized that I was at fault and reopened the investigation.
Signing off for today - Falcon