I think the OP struggled over the difference between

 ...
 my $txt='-UK 123 123-UK 123-UK 123-UK';
 print "|$1| - match until pos:" . pos($txt) . "\n" while $txt=~/((?:\
+d+-UK\W?)+)/g ;
 ...
[download]

and

 ...
 my $txt='-UK 123 123-UK 123-UK 123-UK';
 print "|$1| - match until pos:" . pos($txt) . "\n" while $txt=~/((?:\
+d+-UK\W?)*)/g ;
 ...
[download]

which is the difference between (expr)+ and (expr)*, the latter matching everywhere and (of course) at 'expr', the former matching only at 'expr'.

(maybe I misinterpreted his intention)

Regards

mwa