"Charles Ellson" wrote

That has been alleged to have happened on English south coast
shores/beaches which are screened from the local transmitter by high
cliffs but within range of French base stations.

Certainly has happened at St Margarets Bay (on the coast between Dover and
Deal - Ian Fleming used to live there).

Eurotunnel are equipping the tunnel for mobile phone reception, The South
running tunnel will be connected to French networks, and the North running
tunnel to British networks. So passengers will (normally) be connected to
their home network on the outward journey, but face roaming charges on the
return, with complications in case of Single Line Working.
http://www.eurotunnelgroup.com/uploa...nnelTunnel.pdf

Peter