It was already becoming abundantly clear by the mid-seventies that the DMS was a flawed vehicle that didn't work properly in London, and there was a serious need for something better. The Metropolitans appeared at a time when new vehicles were desperately needed - remember that in the mid-seventies LT still had hundreds of RTs they were desperate to get rid of. According to a 1974 fleet list I have on my bookshelf, there were still over 1300 RTs in stock. Many were trainers or staff buses, but over 800 were scheduled for service each day.Returning to topic, I’d be genuinely interested to hear from anyone who might have some insight on the reasoning behind London Transport’s order for the Metropolitans? E.g. were they ordered due to Leyland’s production/supply problems with the DMS Fleetlines? Or were they seen as some kind of ‘new generation’ bus to supersede the Fleetline?
The B15 prototype from Leyland appeared at the same time, which had a lot of LT input at the design stage, so when the Metropolitan evolved into the Metrobus, and the B15 into the Titan, that was LT's double deck requirements sorted until the mid-eighties.
Given the problems with the MD, I'm surprised LT were willing to trust MCW with orders for almost 1500 vehicles developed from it, but I suppose they didn't have much choice.
As the Ms and Ts came into service, the MDs would have been increasingly viewed as a microfleet by LT standards. They may have been the biggest users of Metropolitans, but 164 vehicles out of around 6000 is small beer.