A planning application for a Tetra mast at 5 Maney Corner, Sutton Coldfield was refused by Birmingham planners in 2003.
O2 Airwavw took this to appeal. Before a decision was made regarding this application O2 Airwave submitted a second application for a Tetra mast which they modified so that this new application did not need prior approval. This application Birmingham planners passed. This second application was also submitted during the main summer holiday period when many residents were away on their main holiday vacations.
At the same location 3 existing 2G T Mobile antennae have been added too. 3 extra 3G antennae have been installed alongside the existing antennae without the apparent need for any permission.( ie permitted development.)

I believe that all applications and extra developments to masts should require full planning permission