We saw a bird on the garden fence the other morning, size about that of a jackdaw, upright stance, crow like black beak. Black head/back/wings, beige throat/breats/sides/belly. Legs I think black but not sure.

It looked a bit like a female bullfinch but:
much bigger
black down all of back
no white rump/wingbars

or a bit like the South Asian House Crow but:
black down entire back
in East Lancashire!

A more sensible suggestion was that of a hooded crow but again the black/pale distribution wasn’t right and there have been no recent reports of hooded crows mating in Lancs. Hybrid hooded/carrion crows have been reported from time to time, mainly near the coast but a pair in Clitheroe in 2008.
Clitheroe isn’t too far from here but it’s unlikely.

More likely, it was a leucistic crow/jackdaw. Leucism occurs when a genetic mutation prevent the normal expression of melanin (usually) in the plumage, leaving the bird with a ‘bleached-out’ look. Whilst they may be of interest to birders, leucistic birds are exposed to predators (as they lack the usual camouflage) and may struggle to attract mates.

Sadly, it didn’t stay long enough to be photographed.