The BMC Competitions Department started in 1955 and finally closed its doors in 1970 but they were not exactly friendly towards to owners who wished to upgrade their cars completely the opposite in fact.
Finally they mellowed towards the enthusiasts and started up Special Tuning in 1963 and this went on to outlive the competitons department and survived until the late 1970's.
Of all the tuning companies offering parts to make your BMC car go faster, you would expect that the BMC Competitions department and later the Special Tuning or S.T. Department would have been one of the most influential and long lasting.
If you thought this, you are wrong. For many years BMC were not interested in selling tuning equipment to the general public, the Competitions department had an ongoing policy of telling the general public to go away.
Eventually, BMC did realise the benefits of marketing "their own" products. Many of these were manufactured for BMC by Downton and others like the 8 port heads by Arden.