There is a new property on Wikidata, P4755, for UK railway station codes (e.g. BNS for Birmingham New Street):, as used by many ticket-booking and live-timetable websites.
Now just 72 stations lack their station code on Wikidata:
https://petscan.wmflabs.org/?language=en&project=wikipedia&depth=3&a...
compared to over 2,500 that have them.
Please help to add the last few.