I always liked the “roarers” (class 81-85) and chased them for haulage from 1982-1990. The “mags” didnt seem to share our enthusiasm for the class (especially Ned News) but who cares, the howls, screams, pops, whines, roars and arcing pantograph of a hard working class 81-85 on 13 Mk i’s took some beating….
Some of those varied roarer sounds linked here

Tony Ewer’s superb portrait of 81001 arriving at Bletchley with an evening “Cobbler” on July 29th 1983, happy days on the WCML.
The Trains “roarers” sometimes did….
1B09 the 1815 Euston – Northampton “Cobbler” remembered
1K09 the 1025 Euston – Crewe remembered
1A76 the 1730 Birmingham – Euston remembered
1F90 the Euston – Liverpool Sunday morning relief
Class 81 – 85 in Scotland, most have worked a variety of pass turns

83001 stabled at New St holding sidings in October 1981
Some moves chasing “roarers”
A big fish to Edge Hill, Jan 86
Chasing “roarers”, Aug 90 – nearing the end…
Individual roarer tales, phots and gen
81001 detailed workings gen 1965-1983 , with phots
85023 on the Saturday Cobbler, June 87
85032 a “roarer” called “patch”

85101 at Walton with the Roarer Requim tour, June 30th 1991
Railtours – not many!