It is interesting here, that ZTL lists the Malayan Sambar as a former species. In G&G thread @lintworm also was not sure is this real Cervus unicolor equina ( syn. malaccensis ).
Thank you @lintworm ! So this is actually Indian sambar deer (Cervus unicolor nigra), according to ZTL.
The correct subspecies should be Cervus unicolor unicolor, than.
@twilighter their Malayan Sambar were sent to Port Lympne (via Howletts) in the UK. I'm not sure where the Indian came in from. Possibly from Port Lympne as that's what they previously held?