With some help, I now come up with thirteen blokes...which includes 2 with dual NZ/British citizenship-- Kevin DuPuy and Paul Smith. Kevin has since returned to the UK, but Paul is a resident of New Zealand. Note that Paul Smith is the only person on this list with 2 winters...
I still suspect that there may have been one or two more, especially for SPASE, which originally had extensive British involvement.
Williamson Ross SPT U. of Chicago 2009 Smith Paul Plumber/UT RPSC FEMC 2008, 2007 Padin Stephen SPT U. of Chicago 2007 DuPuy Kevin sheetmetal worker RPSC FEMC 2004 Balm Simon AST/RO SAO* 1996 Hart Simon AMANDA U. of Wisconsin 1996 Jones Andrew astrophysics NOAO** 1995 Coulthard Andy SPASE Leeds/Wisconsin 1993 Surrey Peter SPASE Leeds/Wisconsin 1992 Chan John K SPASE U. of Leeds 1991 Finnemore Michael SPASE U. of Delaware 1990 Walker Alistair SPASE U. of Delaware 1989 Smith Nigel SPASE U. of Delaware 1988 *(Smithsonian Astrophysical Observatory) **(National Optical Astronomy Observatory)