Thanks to Gaff for an elegantly themed puzzle. Definitions are underlined in the clues.
Today’s the 250th anniversary of the birth of the person hidden in the 1st row. Solutions include a description of him, titles and bits of his works, his home for a time and its location. I think I’ve identified them, but I’ll leave it to solvers to do so for themselves.
(His brother’s descendant was a composer, so that might be the link for one of the other solutions.)
Across
1 Maybe foils Nazis, keeping promise (6)
SWORDS : SS(abbrev. for the Schutzstaffel, a paramilitary organisation of the Nazis) containing(keeping) WORD(promise, as in “you have my word that I’ll do it”).
Defn: Examples of which/maybe are foils, used in the sport of fencing.
4 Respected wolf hurt badly (8)
WORTHFUL : Anagram of(… badly) WOLF HURT.
10 Nice for one to carry laptop after fifty one, legally (7)
LICITLY : [CITY(an example of which/for one, is Nice in France) containing(to carry) 1st letter of(…top) “lap“] placed after(after) LI(Roman numeral for “fifty-one”).
11 Down a bit of fresh coffee before noon (7)
FLATTEN : 1st letter of(a bit of) “fresh” + LATTE(coffee made of espresso with milk) placed before(before) N(abbrev. for “noon”).
Defn: To knock or bring to the ground.
12 Rate sound as a bell (4)
TOLL : Double defn. 1: …/an imposed payment
13 Very soft pine for one backing possibly grand houses (10)
PIANISSIMO : [Reversal of(… backing) [MISS](pine for, as in “I miss you so!”) + I(Roman numeral for “one”)] contained in(… houses) PIANO(a model of which/possibly, is the grand).
Defn: …, as a direction in a music score.
16 Part of area perfect for harvester (6)
REAPER : Hidden in(Part of) “area perfect“.
17 One could be tied to one sort of cheese (7)
COTTAGE : Double defn: 1st: One is tied to it if, only by reason of being an employee, one is allowed to rent it from one’s employer.

20 Mid-sixties trainee in abbey (7)
TINTERN : Middle letter of(Mid-) “sixties“+ INTERN(a trainee in an organisation).
Defn: … in Wales.

21 Herald turnaround in silver market (6)
BODEGA : BODE(to herald/to foretell) + reversal of(turnaround in) AG(symbol for the element, silver).
Defn: … in a Spanish-speaking country.
24 Accessory to gripping play about court (6,4)
TENNIS SHOE : Cryptic defn: What would help a player to control/have a grip on his/her movements on a tennis court.
25 Unrepentant singer (4)
PIAF : Cryptic defn: Reference to a songstress, one of whose famous numbers was the French “Non, je ne regrette rien”, translated as “No, I do not regret anything” ie. I’m unrepentant. English versions were entitled “No Regrets”. Nice!
27 Hermit crab useless without bass, sadly (7)
RECLUSE : Anagram of(…, sadly) [“crab useless” minus(without) “bass“].
29 Heath hedges? Warning: prickly! (7)
THORNED : TED(Heath, former UK Prime Minister) containing(hedges) HORN(not so much as a warning; more of a device to sound a warning).
30 Complaint resulting from airborne reproduction (3,5)
HAY FEVER : Cryptic defn: What is caused by pollen/means of reproduction being borne in the air.
31 Container ship (6)
VESSEL : Double defn.
Down
1 Single bean plant covers wild trail (8)
SOLITARY : SOY(the plant producing soya beans) containing(covers) anagram of(wild) TRAIL.
2 Colonialist excited by swinging (11)
OSCILLATION : Anagram of(… excited) COLONIALIST.
3 Tax burden (4)
DUTY : Double defn: 2nd: An obligation to do (something).
5 Switch options intermittently (3,3,2)
OFF AND ON : The two options/positions of an electrical switch.
6 Change into trainers without hesitation (10)
TRANSITION : Anagram of(Change) “into trainers” minus(without) “er”(an expression of hesitation”).
“Change” doing double duty.
7 Meet one wrapped in paper (3)
FIT : I(Roman numeral for “one”) contained in(wrapped in) FT(abbrev. for the Financial Times, the newspaper).
8 Capital letters only needed definitely on names/initials (6)
LONDON : 1st letters, respectively, of(…/initials) “letters only needed definitely on names“.
Defn: … city.
9, 23 Writers of old rest policy replaced (5,5)
LYRIC POETS : Anagram of(… replaced) REST POLICY.
14 Constituents making detailed admission about passbooks (11)
INGREDIENTS : “ingress”(admission/access) minus its last letter(detailed …) containing(about) [DIE(to pass on from this world) + NT(books in the Bible)].
15 Spinner provided turn at long last in the middle (10)
CENTRIFUGE : [IF(provided/on condition that) + U(an about turn) plus(at) last letter of(… last) “long“] contained in(in) CENTRE(the middle).
18 Lakeside village agrees with Mr Silly (8)
GRASMERE : Anagram of(… Silly) [AGREES plus(with) MR].
19 Bulb‘s raised cover gone these days (8)
DAFFODIL : Reversal of(raised, in a down clue) [LID(a cover for a container) + OFF(gone/departed) + AD(abbrev. for “Anno Domini”/these days, in contrast to BC)].
22 Celebrity cheerleaders’ energy store (6)
STARCH : STAR(a celebrity) + 1st 2 leters of(…leaders) “cheer“
23 See 9
26 Bird swooped (4)
DOVE : Double defn.
28 Keen to be involved in encryption (3)
CRY : Hidden in(involved in) “encryption“.
Defn: … over a dead person.
For 6d, since I don’t like the use of double-duty, I’d rather take it as an &lit relating, perhaps, to one of the transitions in a triathlon.
I remember not long ago reading that DOVE for DIVED is an Americanism which surprised me. I believe it used to be acceptable in the UK but moved out of favour.
Thanks to Gaff and scchua.
I recall finding the word ‘dove’ for ‘dived’ in Jane Austen
Very nice indeed.
What copmus said.
Having heard Prince Charles reading ‘Tintern Abbey’ on the Today programme this morning, to mark Wordsworth’s birthday, I would have been disappointed if this had not been the theme of this ‘anniversary puzzle’.
Thanks for the blog, scchua. At your invitation, I’ll mention LYRIC POETS, DOVE COTTAGE, DAFFODIL[s], TINTERN [Abbey], The SOLITARY REAPER, The THORN, and DOVE COTTAGE, GRASMERE. There may be other references to poems but these are the ones I recognised.
Many thanks to Gaff for a lovely tribute.
Sorry – the comment @4 was mine!
Thanks Gaff and scchua
Adding to Eileen’s list, care of Wikipedia there are also:
LONDON, 1802 and THE RECLUSE
He’s always been one of my favourite English poets – “SHE DWELT AMONGST THE UNTRODDEN WAYS” was a very special poem to me for a long time.
An enjoyable solve which I finished with the excellent PIAF clue on my third sitting.
…and the Ode to DUTY.
Thanks Gaff, scchua
Generally enjoyable, afraid I missed the Wordsworth connections being almost a total ignoramus when it comes to poetry. I like Hovis’s interpretation of TRANSITION which I think makes it a very nice clue.
I found all three of the cryptic definitions rather odd: in PIAF and HAYFEVER I can’t see any cryptic reading in the clues, and for TENNIS SHOE the clue makes no sense read literally.
In 14d, you can also {as I did} get to INGREDIENTS from ENTERING {admission} and IDS {passbooks}, though I’m confident that scchua’s parsing {using de-tailed to chop an S off INGRESS} was what Gaff intended. My LOI, 25a, is a fine clue, in a very nicely themed crossword.
Failed at 20a as I carelessly wrote AINTREE (*TRAINEE) so also could not get GRASMERE (*MR SILLY). This is a lesson that I should be more careful.COD the wonderfully hidden CRY. THANKS Scchua and setter.
Sorry, GRASMERE* AGREES MR
We heard the anniversary mentioned on radio this morning so we soon twigged the theme. That’s two themes, albeit different, today (see Radian in the Indy).
We got it all but couldn’t parse PIANISSIMO (guessed from definition and gradually confirmed as we got the crossers). TENNIS SHOE was our LOI once we realised that 2dn ended in -ion, not -ing.
Thanks, Gaff and scchua.