Two teenagers have been arrested in connection with vandalising heritage railway carriages used in the filming of ITV drama Downton Abbey.
The carriages on the North Yorkshire Moors Railway in Pickering were damaged overnight on 22 July.
Two boys, both aged 17, had been arrested and released while under investigation, North Yorkshire Police said.
The force has asked people who may have images of the incident to contact them.
Damage to the teak carriages, which date from 1930 to 1950, was extensive with windows smashed, furniture and fittings damaged.
The charity which runs the heritage railway said it was unable to estimate the cost of repairing the set of eight carriages but said it would "run into thousands".
It said it had been "overwhelmed" by support and had received almost £20,000 in donations in less than 24 hours.
The carriages are owned by several groups and individuals and were restored by the London and North Eastern Railway Coach Association, a volunteer-run, charitable organisation which restores heritage coaches.
They are used and maintained by the North Yorkshire Moors Railway and have appeared in numerous television shows and films.