Gavin tells Stacey they're leaving BIllericay at 0900 and will be in Barry Island for 1200.
Even with empty roads that journey is over 200 miles would take close to 4 hours, closer to 5 if you left at peak traffic time of 0900.
Even with empty roads that journey is over 200 miles would take close to 4 hours, closer to 5 if you left at peak traffic time of 0900.