The 'heyday' of Bmi is difficult to define; it has always been by definition the underdog. It could be argued that this was one of the things that set it apart. Having established a base at LHR with a view to taking on BA on it's trunk routes, it built a network of routes (and a portfolio of slots) that gave it real potential to make a difference.
The tie-up with DLH & Star Alliance was probably the turning point in many people's view. With the potential to have losses partly underwritten by the two other major shareholders (DLH & SAS), It seems that SMB took his eye off the ball regarding the spirit in which the airline got to this point; it was now nothing to do with building a rival airline to challenge the many state airlines around Europe - it was now all about stripping anything of worth from the operation & forcing the sale to DLH at the end of 10 years. Someone's got the money now, but it's nowhere to be seen anywhere around LHR. Maybe Robert Peston would like to do another interview as he did before the chairman scuttled away without even a company announcement of his departure; except this time he could ask a few searching questions about what happened to the loot.
The merger with BMED was a positive move & generated some cash for a while; recent events have proven the saying of not to have all of your eggs in one basket.