Across:
   1. British busking without American musician (1 1 4)
   5. Very full and quite loud in arrangement of 26 (7)
  10. We rode on the back of sheep!? (3)
  11. see 19 across
  12. Zeffirelli, cultured, brought back favourite of 1 (7)
  13. Spots for the very young in computer industry (5)
  14. Ability of rank passed ten (9)
  15. Horror and disappointment expressed with less fun arranged (9)
  18,5dn. Actor's training short and to the point; students' essentially the same (5 7)
  19,11. Spoil beginner with 1 and popular second singer (5 7)
  20. Program brings up judges (9)
  23. Comedic Rick eternally entertaining the sporting gentleman? (9)
  25. Drain running to low point (5)
  27. Developed a brain chasing a horse (7)
  28. Vehicle with distinctive rear, a 21 (7)
  29. Even out dough? Obviously! (3)
  30. After low, dreads getting high? But getting high is what you do on these! (7)
  31. "Help!", a song mostly a hit for 19 across 11 (2 4)
Down:
   2. see 19 down
:   3. Where you'll find Romans 1:50 added in at the beginning (9)
   4. What to do with young ones in 13... arrange age test? (7)
   5. see 18 across
   6. Pure copper found in nut paste (5)
   7. Test sol-fa arrangement for high voices (9)
   8. Right into endless sweets, and something solid in the kitchen (7)
   9. Shock at a rum cocktail (6)
  16,21. Upset friend and pore over first half of scheme for vehicle maker (9 7)
  17. Juice dads up (3)
  18. In battered pail, prawn not excitingly packaged (9)
  19,2. After this guy who sings "ah" (C), I'm the same either way (7 5)
  20. Waits on test and treatment (7)
  21. see 16
  22. Israel bombed one after another (6)
  24. Retro chef in kitchen definitely has one (5)
  26. One abandoned duties carelessly, but 19 down 2 performed many (5)
Solution:
=BBKING=STUFFED|
T=U=N=EWE=N=A=R|
ROBBINS=LUCILLE|
A=L=T=T=L=U=S=S|
UTERI=ADEPTNESS|
M===A=T=R===T=E|
AWFULNESS=PETER|
==E=L==A==L=O==|
MARTY=APPRAISES|
I=D===T=O=I===E|
CRICKETER=NADIR|
H=N=N=E=S=W=U=I|
ARABIAN=CARRERA|
E=N=F=DUH=A=T=L|
LADDERS=ELPASO=|
Name: 866 - British Busk
Author: by BenDR