I haven't encountered that many singing Firecrests before. The most treasured of my experiences was in my garden in spring 2016. This bird eclipsed even that extrovert performer.
Although it largely kept to the shade, it showed very well indeed. Another bird (perhaps a female) was nearby, but stayed shy of the camera. The male just kept on singing, however.
My book-after-next is one about the finest walks in my adopted home county of Norfolk. It's a book of year-round wanders, so I need to a selection each season. Yesterday was the turn of NW Norfolk. As I drew up in an inauspicious car park, I could hear a Goldcrest singing in the firs above. As I got out of the car, it was joined by a Firecrest. This bird proceeded to sing at very close range, just above head height, for a few minutes.
Firecrests are not a bird I ever expect to tire of. Every single moment spent with them is a blessing. The 'Firecrest Day' at Portland Bill last October will particularly stick in my memory bank into perpetuity.