It seems that some parents will have less to worry about in the near future.  Vodafone and Orange are to start sharing base stations reducing maintenance costs whilst improving coverage.  This comes hot on the heels of the union between 3 and T-Mobile to share their HSPA networks. 

But there could be a big problem in the future.  If the government has its way (they need the money) the 900MHz spectrum could be seized from Vodafone & O2 and resold.  Perversely this would lead them to rely on using the shorter range 1800MHz GSM frequencies requiring more base stations in the street!