Tachyporus chrysomelinus/dispar (Linnaeus, 1758)
Photo in preparation
Tachyporus chrysomelinus is widespread and very common throughout the UK and Europe, it may be common throughout Watford as, identified from Joy, we have many specimens under this name in our collections. However, R.G.Booth ¹ shows that the closely similar T.dispar (Pk.) is also common throughout the UK and that the two species may occur together. T.dispar is (obviously) not featured in Joy's work. To provide local records the aedeagi need to be examined. This work is in Hand.

¹ Booth, R.G. 1988. Identity of T.chrysomelinus (L.) and the separation of T.dispar (Pk.) 107: 127-133.