I can only offer other people's learned discourse as I have not seen anything similar. The reason I have not offered this so far is because I haven't yet worked out how to get up and down stairs with a crutch in each hand and carry fungi books. A rucksack may be the answer.
However, a helper has provided me with some relevant literature.
As we have no microscopic details we will have to make some assumptions. We are looking at a pleurotoid fungus so let's assume it is white spored - you would have been able to make a best guess from the gills. And to get to
Lentinellus the edge of the gills would have been noticeably serrate or toothed.
Assuming we are safely at
Lentinellus let's go with the key in British Fungus Flora 6 on crepidotoid and pleurotoid agarics.
1. Stems distinct, central or slightly eccentric... 2
x. Sessile, or stems short, lateral or reduced to a basal plug... 6
From the photo I'd go with second option leading to step 6 in the key.
This leaves only three options separated in the key by microscopic characters. Lacking this information here's the text on them from the Basidiomycota Checklist:
Lentinellus laurocerasi
Habitat: On dead wood. British material on Prunus laurocerasus.
Notes: Know only from the type, from Denbighshire (Coed Coch) in 1879. Doubtfully a species of Lentinellus, since it has unornamented spores.
Lentinellus flabelliformis
Habitat: On decayed wood of deciduous trees or conifers.
Notes: Two collections, from Angus (Glamis) by J. Stevenson in 1872 and 1873. Confused with Lentinellus omphalodes which is unknown in Britain.
Lentinellus ursinus
Habitat: On decayed wood of deciduous trees in old areas of woodland. Usually on large fallen trunks or stumps of Fagus and rarely reported on Salix spp.
Notes: Known from Berkshire, South Essex, South Hampshire, Surrey and West Kent.
Lentinellus ursinus has a smell that is described as "fairly strong, acid-fragrant, peculiar". The other two species do not have a distinctive smell.
So assuming the smell fitted that described for
L. ursinus, you could probably safely narrow it down to this species when combined with the information from the Checklist.
As for
Lentinellus vulpinus, this would not have a distinctive smell and would have a cottony or woolly surface to the "fruiting bodies", as compared with a velvety tomentose surface in
L. ursinus.
Hope this helps.
Ken