The Ford Zodiac
Unusually for the UK, this was an 1950s American-style car which sold rather well. With a bench seat, column-mounted gear change and a handbrake that you pulled out of the dashboard rather than up from the floor, it cashed in on the US fashion craze (it was the era of drape jackets, DAs and Teddy boys). The Zodiac had classic '50s styling, including lots of chrome, big tailfins, huge rear light clusters and double headlights, as well as big (for the UK) V4 and V6 2.5 and 3 litre engines, and bumpers which could cause serious damage to military vehicles. Perhaps for this reason, many police forces used them - they were fast, reliable and above all, looked tough.
The Zodiac was the last 100% British-built Ford - after this, Fords began to include more imported components. The car was sold between 1954 and around 1969 and qualifies as a British 'big iron' car. Built at Ford's Dagenham plant, they were superceded by the more luxurious, if somewhat duller Granada (similar to, if larger than the Cortina).
Full of character, this was one car I miss seeing about on the roads - the OTT styling, thumping engine and muffled, slightly gruff exhaust noise gave them a charm all their own. There is a small but enthusiatic band of people who collect and restore them still.
Pictures at http://ourworld.compuserve.com/homepages/Norman_Watkins/Zodiac.htm