Since this is a popular BBC series, "proper" subtitles (synced and formatted) are widely available on reputable subtitle databases. Search for the following filenames to ensure compatibility with standard releases:
Ghosts.S02E07.The.Ghost.of.Christmas.en.srt Ghosts subtitles English S02E07
Search for Ghosts.UK.S02E07.The.Ghost.of.Christmas.English.srt Since this is a popular BBC series, "proper"