
Now, I have not steeped hops like this before and I am a little disappointed to find that after some time in the keg, the aroma and flavour have first mellowed and then after around a month, mostly disappeared

In order to make sure it is not caused by something I am doing when transferring to keg, I have left the latest brew in the fermenter and through sampling it regularly I have noticed the same effect as the brew in the keg.
Does this experience seem normal to what you have experienced?
Assuming I am not doing something daft, I assume the only way to prolong this aroma and flavour is to dry hop in the keg?? If so, I had better get myself a pingpong ball and a muslin bag.
Any thought appreciated.