Amid the ongoing and wholesale reorganization of the world’s mobile tower investments, it was only a matter of time before the UK would be further affected. Vodafone has already carved out its tower operations across Europe and mounted an initial public offering (IPO) in the resulting entity, Vantage Towers. Now its UK infrastructure partner, Virgin Media O2 (VMO2), is reported to be preparing to sell half of its stake in Cornerstone, their towers joint venture. Cornerstone Telecommunications Infrastructure Limited (CTIL) was formed as a 50:50 joint venture by the UK arms of Vodafone and Telefónica O2 (the latter now part of another 50:50 UK joint venture, VMO2, between Telefónica and Liberty Global). Cornerstone evolved from a passive infrastructure sharing venture…