Certainly an interesting development. We already have 2GW of either-way interconnectors between GB and France, and a new one has recently been constructed to the Netherlands.
Note that this will also allow British power to be exported to France, such as during peak French demand: France uses primarily nuclear power with a little hydro, gas and coal. Nuclear isn't very switch on-off able so British gas power generally fills the gap. The rest of the time Britain is generally importing French nuclear electricity which is otherwise surplus to requirement. Of course there are exceptions, such as during the recession when the value of GBP declined sharply compared to the Euro... Britain-France interconnector is priced in GBP so as a result our electricity looked very cheap to the French and the interconnector went into export mode for us almost constantly.
