Finn is sometimes referred to as being thirteen, sometimes twelve.
The trains at the Liverpool - Dublin railway/Ferry terminus are neither British Rail locomotives or in Standard British Rail Blue & Yellow livery. This scene was quite obviously filmed in Eire on the Irish Railway network with only a token attempt (a loudspeaker announcement in an English accent) to hide it.
The ferry terminal in Liverpool has never had a railway station next to it. The nearest station is Liverpool Lime Street which is around one mile away to the east, and the railway station used in the film is clearly too small to be Lime Street.