paul i found this australian site ,
again ive no idea how the company are for service or who they are but they have it listed as a kilt liner a term i think seems to be more approptraite than the term underkilt that we all use on here

some folks just dont like the connection with underskirts ive noticed

anyways here it is
http://www.activskin.com.au/shop/index.php?cPath=24

its about 16 uk pounds not inclucing postage worth a email though