If you go online, sleeping dragon, there is plenty of evidence of a number of the Wexfords being available on DVD in recent years, but some of the references are 5 years old so may be out of date. However, you should know (you may already know) that 3 Wexford titles are not only not available on DVD they have not been repeated on television. When I challenged the satellite station which was reshowing the Wexfords ( Gold?, ITV 3?), they told me that the company which owned the rights had forbidden their transmission. No reason given or known.
The 3 "missing" titles are Wolf to the Slaughter (1989), No More Dying Then (1989), Put on by Cunning (1990).If you have these titles on video have them transferred to DVD!