The price of copper has risen by 300 percent over the last two years. Other metals have also risen in value. According to GB2RS News, this is making radio amateurs targets for copper thieves. An amateur in Yorkshire had all his cabling stolen including the coax and ladder line for his G5RV antenna.
I presume the action of an irate neighbour fed up with receiving TVI has been ruled out. The RSGB is encouraging amateurs to make sure access to cables is restricted and that their installations are as secure as possible. Looks like another benefit of stealth operation and attic antennas!