The only thing that works from BOH (as has been demonstrated countless times over the years) is low fares and holiday/package flights that are not offered from SOU. This gives BOH a bigger than otherwise catchment area as people will travel from further distances to access the low fares.
What's odd at the moment though is that fares on some TUI services are much higher than those from LGW or LTN so it seems to me that demand is outweighing supply.
Eventually this will naturally lead to additional aircraft from TUI or spill over from another airline after BRS and London gets full.
What gets me upset is that this type of 'organic' growth only gets delivered every 10-15 years! If MAG was half as 'proactive' for BOH as it is for EMA, MAN, STN then we would be seeing more activity more quickly.
What do I mean by proactive? By slashing the cost of flying in and doing business at BOH. Right now the costs are sky high - higher than London airports for sure.