Cryptic
Across
1 Unduly risk, say, rearrangement of Japanese chain (6,7)
10 Ancient civilization of old city-state about to be surrounded by a separatist movement (7)
11 African river: take a first-class trip to see the country (7)
12 Characters even use a little sister, covering informally for those from down under (7)
13 Areas dotted about Los Angeles, a throwback to Asia, in the main? (4,3)
14 Put in charge after detailed Christian celebration is suddenly revealing (9)
16 Impress a Bahamian, giving an insight on the state of Malaysia (5)
18 French island or a return, maybe, to a town in W Nigeria (5)
20 Followers of John introduced method into Church matters (9)
22 British Royal Family in Uganda getting evacuated to another African country... (7)
24 ...some money in southern Rwanda initially, linked to Diana? (7)
25 Exchanging gold to get shares in Baltic port (7)
26 One leaves resort near Rome, taking in part of the Côte d’Azur on return to Moravian city (7)
27 Peneplains? Lot being metamorphosed Swiss-Italian peaks (9,4)

Down
2 Where Prince Andrew’s going to rent? (9)
3 It describes their state, unofficially – utter dog’s dinner! (7)
4 Where people from 8, for example, climb to be in their natural surroundings? (5)
5 Oscar’s man settled into island in the Gulf of California (3,6)
6 The vowel, consonants between E and I, and indefinite articles, troubled folk in Asia (7)
7 She’s a part of ancient Greece (5)
8 Reburying Kate, dug up in a city in the 4 (13)
9 Religious type’s character at the end shows at Arthurian’s perfidy (13)
15 Additional outlet for bloodstock sales in Britain (9)
17 Northern suburb of Paris doesn’t look or sound like the place of Beecham’s origins (9)
19 Corin looks odd in a pair of specs in Venezuelan valley (7)
21 Classical Greek site, a complex built by father and daughter? (7)
23 Russian, with English and French translation? (5)
24 One from Chelsea loses bearing somewhere south of Las Vegas (5)

Quick
Across
1 Japanese archipelago which includes Okinawa (6,7)
10 Pre-Roman region of Italy (7)
11 Most populous African nation (7)
12 Familiar Antipodeans (7)
13 Lake between Kazakhstan and Uzbekistan (4,3)
14 As a god-like manifestation (9)
16 Malaysian state on the island of Borneo (5)
18 W Nigerian city, NW of Ibadan in Oyo state (5)
20 Methodists (9)
22 African country, formerly Upper Volta (7)
24 British aristocratic family whose seat is Althorp House, Northamptonshire (7)
25 German Baltic port (7)
26 City of the Czech Republic, the capital of N Moravia (7)
27 Mountain chain straddling the central part of the Swiss-Italian border (9,4)

Down
2 English county, the largest in area until reorganization in 1974 (9)
3 Relating to an Aryan Islamic mountain people of the Middle East (7)
4 Mountains forming the natural boundary between Europe and Asia (5)
5 Mountain city of Guatemala: island off Baja California (3,6)
6 Mainly Pashto-speaking people of S central Asia (7)
7 Part of ancient Greece, covering the Peloponnese, Crete and Rhodes (5)
8 Russian city, Sverdlovsk 1924-91 (13)
9 Studier of the Avesta (13)
15 Home of the Jockey Club in Britain (9)
17 Suburb of Paris in the Oise translated as ‘Fair field’ (9)
19 The largest river emptying into the Caribbean from S America (7)
21 Site of town in the classical Messenia region of SW Greece: daughter of Agamemnon (7)
23 ‘Ballet -----’, one of many identically named dance troupes based on Diaghilev’s original (5)
24 Desert town south of Las Vegas, Nevada (5)

Big Bad World by P J Polyp