(22/2/23, Aberystwyth) 158837 on 1I20 1330 AYW-BHI passing a shunter with ballast on the VoR Railway 

A good thing captured from a bad spot 😂
Thanks to the drivers of both trains for a tone from each 😜
The 158's low tone horn is incorrect for a 158/159 at 311Hz (D#4/Eb4), which is meant to be the low tone horn of a 150/153/155/156.
The correct 158/159 low tone horn would be 370Hz (F#4/Gb4), which is the same as the high tone horn of a 150/153/155/156.
The 158 high tone horn is even higher at 622Hz (D#5/Eb5), so on 158s with incorrect replacement low tone horns, the low and high tones are an entire octave apart.