Answer and annotation for 20D left for a rookie commenter till 10 AM
ACROSS
6 Keep Pound in Switzerland (5) BASEL {BASE}{L}
7 Poor long suffering creature (8) PANGOLIN {PA{LONG*}IN}
10 Late prospect, showing no response (7) DEADPAN {DEAD}{PAN}
11 Father of three, Turkish leader died for his country (7) PATRIOT {PA}{TRIO}{Tu...h}
12 General way to make it bigger (7) ENLARGE*
13 Plant material by one in Germany (7) MULLEIN {MULL}{EIN}
14 Chronic type, worried about fireworks (11) PYROTECHNIC*
19 Can hit the sea in France (7) SLAMMER {SLAM}{MER}
21 A newspaper takes on a system of rules (7) ORGANON {ORGAN}{ON}
23 Not only noisy, in fact led on (7) DELUDED {DE{LoUD}ED}
25 Free trial allowed, provided it's an emergency rescue act (7) AIRLIFT {AIRL{IF}T*}
26 Making a mark and entering land (8) BRANDING {BR{AND}ING}
27 Ability to express oneself only makes it piquant (5) ORACY {O}{RACY}
DOWN
1 "Sit up and take a call on meet", you're told (8) ESCALLOP {ES{CALL}OP<=} (~ meat)
2 He took to his heels on European upraising (6) ELOPER {RE}{POLE}<=
3 Nothing confidential in such a missive (4,6) OPEN LETTER [CD]
4 Break up vessels (4) SNAP<=
5 The German drinks French wine, I guess (6) DIVINE {DI{VIN}E}
6 Harry's an animal (6) BADGER [DD]
8 Algerian port has many hoisting bunting (7) ORTOLAN {OR{LOT<=}AN}
9 Way to store wine in a cask, it's a gimmick (5) STUNT {S{TUN}T}
13 Make fun of one under shade of shrub (4,6) MOCK ORANGE{MOCK} ORANGE Anno pending (Addendum - {MOCK} {ORANGE} - See comments)
15 Month in Spain — nothing for a month, return (7) RAMADAN {NADA}{MAR}<=Why "in Spain"? See comments
16 Group takes over, bar a man-eater (8) CANNIBAL {CA{INN<=}BAL}
17 Ideas to get away (5) ASIDE* &lit
18 Not among the pigs, too big for one's breeches (6) SNOTTY {S{NOT}TY}
20 Attraction, boy turns out to be Royal blue (6)A?L?R? (Addendum - ALLURE {RoyAL+bLUE}* [CA] - See comments)
22 No booze, get high monster! (6) GORGON {NO}{GROG}<=
24 Drop or push up a tit, say (4) DRIB<=
GRID
6 Keep Pound in Switzerland (5) BASEL {BASE}{L}
7 Poor long suffering creature (8) PANGOLIN {PA{LONG*}IN}
10 Late prospect, showing no response (7) DEADPAN {DEAD}{PAN}
11 Father of three, Turkish leader died for his country (7) PATRIOT {PA}{TRIO}{Tu...h}
12 General way to make it bigger (7) ENLARGE*
13 Plant material by one in Germany (7) MULLEIN {MULL}{EIN}
14 Chronic type, worried about fireworks (11) PYROTECHNIC*
19 Can hit the sea in France (7) SLAMMER {SLAM}{MER}
21 A newspaper takes on a system of rules (7) ORGANON {ORGAN}{ON}
23 Not only noisy, in fact led on (7) DELUDED {DE{L
25 Free trial allowed, provided it's an emergency rescue act (7) AIRLIFT {AIRL{IF}T*}
26 Making a mark and entering land (8) BRANDING {BR{AND}ING}
27 Ability to express oneself only makes it piquant (5) ORACY {O}{RACY}
DOWN
1 "Sit up and take a call on meet", you're told (8) ESCALLOP {ES{CALL}OP<=} (~ meat)
2 He took to his heels on European upraising (6) ELOPER {RE}{POLE}<=
3 Nothing confidential in such a missive (4,6) OPEN LETTER [CD]
4 Break up vessels (4) SNAP<=
5 The German drinks French wine, I guess (6) DIVINE {DI{VIN}E}
6 Harry's an animal (6) BADGER [DD]
8 Algerian port has many hoisting bunting (7) ORTOLAN {OR{LOT<=}AN}
9 Way to store wine in a cask, it's a gimmick (5) STUNT {S{TUN}T}
13 Make fun of one under shade of shrub (4,6) MOCK ORANGE
15 Month in Spain — nothing for a month, return (7) RAMADAN {NADA}{MAR}<=
16 Group takes over, bar a man-eater (8) CANNIBAL {CA{INN<=}BAL}
17 Ideas to get away (5) ASIDE* &lit
18 Not among the pigs, too big for one's breeches (6) SNOTTY {S{NOT}TY}
20 Attraction, boy turns out to be Royal blue (6)
22 No booze, get high monster! (6) GORGON {NO}{GROG}<=
24 Drop or push up a tit, say (4) DRIB<=
GRID