Inspector Burke says 'You're right they're heading North ... Have all key points covered from here into Norwich." If that's the case then they're heading East.
The gang are using a travelling fair as a cover and are heading for Blackpool. With Blackpool being full of amusement arcades and their own pleasure beach a travelling fair wouldn't have been allowed in as there would be no space for one and they'd be taking trade from the resident stall holders.
Barton and Snowey are captured in the Blackpool Winter Gardens and are put into the Snake House which is unlikely as it's some distance away in a completely different building.
When climbing the tower, Barton has two opportunities to take the protective headphones off the villains to protect himself, but for some reason never bothers.
A key clue for Barton is the 'death tune' played by the villains at the airport, at the first night club, at the circus and so on. Yet it has no role at all, and there is no reason for the villains to play it. Had they not played it, Barton would not have been onto them.
Fouracada is meant to be heading North on the road from St Albans to Norwich, whereas he ends up at Blackpool. From St Albans, Norwich is virtually a dead end.
In the evening at Lord Armadale's house, crickets are chirping. Crickets don't chirp at evening in England, certainly not in the North.