Thank you.
Embedded...tacit...silo...before PERT/CPA, inter-disciplinary, cross-Company UK Aero Projects were managed with paper, with very occasional meetings, all assumed to be called as excuses for a trip out - a "jolly". Even a rail warrant to go, say from Bristol to Wythenshawe, was argued jealously. Projects were driven by two quests: to dodge blame, and to extract more resources for ME! No One was ever in charge. The reason was, of course, money. If...(Bloodhound example) MoS had appointed Ferranti or Bristol to be Prime Contractor, then: a) the true innovators (always seen in MoS as its own relevant Establishment) would be demeaned; and b) Prime would take a handling fee over Subs' invoices. If the whole Project was on cost plus, then so; but if Ministers had chosen to accept an upfront budget increment, to dump risk of over-run onto Prime, then Prime spent his waking days sloping his shoulders so the sh1t could flow down as a loss to Sub. All this meant that the actual analogy for UK Project Management Organisation was not silo but spaghetti.
One reason in 1948 for duplicating Red Heathen, to be Bloodhound and Thunderbird, was the notion that EE could be (vertically integrated, one-stop shop, Prime...all of those things) across EE airframe, Marconi lecky, Napier rocket, such that MoS need only Project Manage/integrate the Bristol Aeroplane+Bristol Aero-Engines+Ferranti job. But they all lapsed into their silos.
That interface with the Customer-as-(meddler-designer) is missing from the MBS Paper.