Whilst not wishing to doubt what your late uncle saw, or believed he saw, I cannot think of any of the twin engine German types with glazed nose (17, 88 or 111) then is use that might have had a ‘red leatherette’ seat in the nose – least of all one that would be visible. I suspect he saw something ‘reddish’…but that takes us no further forward, anyway. Not wishing to be pedantic or nit-pick, but am trying to help unravel the mystery!
You could well be right as, thinking about it, I may have misremembered what he said but I know for certain he could see a seat in the nose.