The "40" series of Dinkys was the first completely new series introduced by Meccano after production resumed following the end of WWII. This series -- all British saloon cars (i.e., sedans) -- included the Riley RMA (#40A), this Triumph 1800 (#40B), the Austin Devon (#40D), the Standard Vanguard (#40E), the Hillman Minx (#40F), the Morris Oxford (#40G), the Austin FX3 taxi (#40H), and the Austin Somerset (#40J). These various models were introduced between 1947 and the early 1950s.
The Triumph 1800 toy was produced by Meccano between 1948 and 1960. In 1953-54, Meccano modified their numbering system, eliminating the alpha-numeric two-numeral-plus-letter identification (#40B in this case) and replacing it with a three-digit numeric ID (#151 in this case). This toy has no number stamped on its baseplate; however, since I purchased it in the U.S. in the mid-1950s, this car was probably produced after the numbering change and is thus technically #151.
The actual Triumph 1800 saloon automobile was produced by the Standard Motor Company between 1946 and 1948, immediately following WWII. The "1800" in the name was derived from the engine size (a 1776 cc straight-4-cylinder OHV engine). Four thousand 1800s were manufactured. In 1949, the car was fitted with a larger engine (2,088 cc) and was renamed the Triumph 2000. And, following some further modifications during that year, it became known as the Triumph Renown, which was produced until 1954. These were considered to be luxury cars.