4017: A Knotty Problem by Homer

This was another clever puzzle from Homer. The theme that had to be discovered was Gretna Green, the town where eloping couples from England could be married without banns, priest or licence and where marriages were performed by the blacksmith or toll-keeper. Two letters were entered in single cells and in the completed grid some letters had to be removed. In the bottom of the grid the letters ELOPERS had to move, leaving ENGLAND. The dotted line, therefore, represented the border between England and Scotland. The letters from ELOPERS had to be transferred to the 11 letter unclued entry to form TOLLKEEPERS. Elsewhere the removals were PRIEST, BANNS and LICENCE. Finally, starting in 27ac, the word GRETNA had to be highlighted in GREEN. This was an excellently themed puzzle with a high quality of cluing which gave Gregson a tricky job.

1 Finding earth in clay is a blow for Edmund (5)
PEISE E (earth) in PISE
5 Amount of money due, tips for session clerk for interment? (8)
SOULSCOT S(ession) C(lerk) in SOU LOT; & lit.
12 Swimmer making comeback requires oxygen and hard work (6)
ROBALO O + LABOR reversed
13 Humming's to be tender when grandchild's around? That's about right (7)
ODORATE OE (grandchild) containingR in DOAT
16 Prepared for Unionist Pastor on Radio 2 (4, two words)
UP TO UP (Unionist Pastor) + TO Homophone TWO
17 Note what Homer says (3)
DOH 2 definitions ref. Homer Simpson!
18 Requiring loft after slicing tee shot, before putting on green with concealed ditch? (4)
GOLF Anagram LOFT less T (tee) + G(reen) less REEN ditch; &lit.
19 Parts of skeleton found buried in Trossachs (4)
OSSA Hidden
20 A small portion without seconds is enough (5)
21 Surgery having confidence old boy's date being used for operation (9)
HOBDAYING HOPING replacing OP with OB + D
23 Link between nerves and strain shows bedding's restricted (7)
24 Saunter into my buffet for dram and kip, possibly (13, two words)
MONETARY UNITS Anagram SAUNTER INTO MY (drams and kips are coins)
27 For example, about 160, or 33 (5)
EGRET EG + RE + T (160) ref 33 across TUFT
31 Llanelli's number eight splits gob securing triple crown (4)
TIAR TAR (sailor=gob) containing I (eighth letter in Llanelli)
33 Somebody wants a newspaper on Tuesday (4)
TUFT TU (Tuesday) + FT (TUFT = a person of some importance)
35 Start to blubber after The King and I? That's a film from yesteryear (3)
WEB WE + B(lubber)
36 Fatted calf? In gospel, last one's sacrificed as spendthrift's back (4)
MART MARK replacing K with (spendthrif)T
38 Rein in American wife wearing scanty gear, showing a hint of undies at the rear (7)
CARIBOU A (American) + RIB in CO(g) + U
39 One hiding in study at Balmoral? (6)
REDCAP READ less A + CAP (Balmoral is a type of hat) &lit.
41 Eastern pork cooked with soy and some odd things (8)
42 Seeds of nippy vegetable added to beef? (5)
SENVY (mustard) NV (first letters) in SEY; & lit.
1 Asian grub could be source of infection contained by Lister (5)
2 Dish that is cold (3)
ICE Anagram IE + C; &lit.
3 He can be found among explorers from time to time, climbing on top of Annapurna (6)
SHERPA HE in SRP (regular letters in EXPLORERS reversed – SreRolPxe) + A : &lit.
4 Could be like a spurtle being twisted (6)
ENSATE ENS (being) + ATE
5 Dizziness and bleary vision results from nips of old malt in the Northern area (8)
6 Acceptable with a couple of Juneberries, these tails of scampi etc could make soup du jour (7)
UROPODS Anagram SOUP DU JOUR less U (acceptable) and JU(neberries)
7 Seen around River Tay, perhaps, a vessel with squarish sails (6)
LORCHA R (river) in LOCH (ref. Loch Tay) + A
8 Acted the part of Oscar in a minor role (5)
CAMEO CAME + O (Oscar)
9 Reckless roofer that's ignoring height is one in the wrong (10)
TORTFEASOR Anagram ROOFER THATS less H (height)
10 Order to hired guns? (11, two words)
11 Like the drone of bagpipes where metre's out of permitted range for piece (5)
REEDY RE(M)EDY (range of coin) Less M )metre
14 Celebrity mostly shown up, following performance, as philistine (6)
GIGMAN GIG + NAM(e) reversed
15 Take short walk in street to get protective headgear (6)
19 With some leads to measure electrical resistance, two of these could be so deployed (9)
OHMMETERS Anagram SOME + MER (initial letters) + TH(ese); & lit.
22 Cancel date, having little energy - time to get sheltered housing (6)
DELETE D (date) + E (energy) + T (time) in LEE
25 Bravely, you state Liberal's an unknown quantity (8)
YEOMANLY YE + OMAN + L + Y (unknown)
26 Here, nerd taking degree might be served by innkeeper (6)
KNEIPE Anagram INNKEEPER less NER(D); & lit. (very clever!)
28 Tinker with saw's close to cut tree (5)
29 Maybe Crewe, with regular departures, features in this? (5)
ABCEE even letters mAyBe CrEwE; & another &lit!
30 Fish found in Slav regions now and again (6)
SARGOS odd letters SlAv ReGiOnS
31 Transactions in Poland get fraction of euro after much changing (6)
TRIPLE TR + I (in) PL (Poland) + E(uro)
32 English MEP roughly thrown overboard from windy promenade deck (5)
34 What might help you to see the light? Fellow's (or female's) statement at altar (4)
FIDO F (fellow/female) + I DO!
37 Pulled up with son for a day's round (5)
PUDSY UP (reversed) plus DAY swapping A for S (son)
40 Drop in meantime (3)
EAN Hidden