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This article is about the castle tunnel. You may be looking for the south tunnel.

Tidmouth Tunnel, also known as the Castle Tunnel, is a tunnel on Duck's Branch Line located between Tidmouth and Tidmouth Hault.

It first appeared in the third series and made numerous appearances until the ninth. The architectural style changed in the later series. Although never mentioned by name in an episode, it was first named in an eighth series learning segment. It returned in Tale of the Brave in the same architectural style as the third series and later appeared in The Adventure Begins and has made infrequent appearances since.

In the television series, this is where James once tried smoking bees off his boiler.



  • Tidmouth Tunnel has had numerous modifications throughout the years:
    • Series 7
      • The lake became significantly smaller.
    • Series 9:
      • A siding was added to the other side of the tunnel.
    • Tale of the Brave:
      • The tunnel's architecture returned to its original design.
      • The lake returned to the size seen in the third series.
  • The Castellated Tunnel is a modified version of the tunnel.
  • The tunnel's model that would appear in the seventh series onwards was first used for a set in the sixth series episode, Jack Frost.