Just when I was in paradise the phone rang.This is the very first Lovejoy novel, published in 1977 and adapted for TV as part of the first season in 1986. It is interesting coming to it after having read more than half of the rest of the series. Very few of the other books are really recognisable as murder mysteries; they tend to spiral off into grand conspiracies involving antiques and treachery, ending without much resolution. But here there is an actual suspicious death involving obscure antiques (the eponymous pair of duelling pistols) and when Lovejoy is called upon to locate the pistols he inevitably investigates the murder as well, and what's more solves it. It is also noticeable that Lovejoy's supernatural ability to detect antiques is a bit less well developed here than in some later books, and that Tinker Dill (played so lovably by Dudley Sutton on TV) is not the repellent character he becomes later in the sequence.
One very negative point: Lovejoy hits his girlfriend in the first chapter. I am surprised that this was acceptable in 1977 and I would like to think that it would not be acceptable now. I suspect that this (and much else) was omitted from the TV adaptation.