Four decades ago today, the nation was slightly startled by the arrival of a dramatic-looking new slice of family car. A wedge-shaped slice, which had come from the by now rather pedestrian Austin-Morris division of British Leyland.

The new 18-22 Series was launched on March 26, 1975, and earlier I attended a modest ceremony to mark the fact at the place of its birth, at what is now BMW’s Mini factory on the edge of Oxford.

Strictly speaking, we were told - by a Mini factory guide who worked there at the time - that the 18-22 was manufactured on the other side of a bypass on land now occupied by a gym, an Audi dealer and a science park, but the 18-22’s body was made on the part of the site from where Minis emerge today.

In case the 18-22 Series doesn’t sound familiar to you, you may remember this car as the Princess, or following a demotion and a sex-change, the Ambassador. The Princess is what it became after nine months, when BL decided to rationalise the original Austin, Morris and Wolseley versions under this one nameplate.

The Princess tends to be lumped with the Morris Marina and Austin Allegro as an example of one of the worst cars produced by Britain’s troubled motor industry in the 1970s, but the 'wedge' differed from this infamous pair in that it was actually rather good.