Superb memories and photos - thank you so much!
That is the C404 I was thinking of.
My grandad gave me a huge model of a National B200, but it wasn't that reg
Re Datapost moved their operation to Coventry, anyone remember when? (late 80's I think). - my grandad retired in 87 and it was a while after that. IIRC, the thing evolved into Parcelforce and they had a BWA Viscount painted up, that was around 91-92 I think.