Also, when did the 3.0si become available in the UK?
3.0Si was introduced in other markets in 1971, US in 1975. As noted above re: equipment, the leather, A/C, power accessories, etc. were only standard in the US market, and not terribly commonly seen in Europe (other than on the 3.3Li). The vinyl in this car strikes me as pretty unusual for the UK, where cloth is more common.
The discrepancy in model availability between the US and the rest of the world speaks to BMW's market position here, which was not as strong in the early '70s as it would become later, the uncertainty at the time around then-new emissions standards, and most of all, tension with US importer Max Hoffman, who BMW was trying to rid themselves of. Funny how, as soon as BMW NA took over in 1975, we got the 3.0Si (1971 elsewhere) and 5-series (1972) and Hoffman's creation, the Bavaria, went away.
Back to the car at hand, if the price calculations done by duct-tape are correct, that's a lot of money for a car with noticeable rust and body filler...but very few RHD cars survive....