If the router is set for a US config then it may be picking channel 12 or 13 for the wireless connection. If the laptop is set to UK then UK law prohibits the use of anything above channel 11.
It's the other way round, viz Wikipedia:
Most other European countries are almost as liberal as Japan, disallowing only channel 14, while North America and some Central and South American countries further disallow 12 and 13.
1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU BB => 2010: Orange 16 Meg LLU BB