We have had all all 5 series on DVD for years. When my wife was still a senior civil servant she used to claim that she watched them for educational purposes. Still, IMO, the most consistently funny sitcoms, right up to the end, and while Nigel Hawthorne got most of the plaudits for his lengthy set pieces, I always felt that Derek Fowlds had some of the best lines, particularly when correcting the PM's grammar or syntax.
I did read an interview with him some years ago in which he came across as quite grumpy about the fact that his two co-stars got so much attention - and MBEs - while he was usually overlooked. It would be sad if that were how he really felt.