Don't think they were ever on OGWt but were on Supersonic in 1977! They split up in 1978, but reforemd in 1988 for 6 concerts. Since 2006 they have done a few more including a mini tour last year culminating in 2 gigs in Tokyo. Didn't manage to get to those but did manage to see them 10 times over the course of the year, from London to Birmingham, Chester, Manchester and of course Liverpool.
Had some good guest singers and guitarists at times including Kevin Rowland (Dexys Midnight Runners), Ian Broudie (Lightning Seeds), and Suggs (Madness), know to Deaf School fans as Mr Bright as he is married to one of the singers Bette Bright. If you get the chance to see them I would reccommend it, you won't be disappointed.