From Wikipedia:
The Jaguar Mark 2 is a mid-sized luxury sports saloon built from late 1959 to 1967 by Jaguar in Coventry, England. The previous Jaguar 2.4 Litre and 3.4 Litre models made between 1955 and 1959 are identified as Mark 1 Jaguars.
The Mark 2 was a fast and capable saloon in line with Sir William Lyons' 1950s advertising slogan: Grace . . . Space . . . Pace, available with all three versions of the advanced Jaguar XK6 I6 engine, the 2.4, 3.4, and 3.8 litre.
Production of the 3.8 ended in the (northern) autumn of 1967,
with discounted sale of the 3.4 continuing on as the 340 until September
1968, and the 2.4 as the 240 until April 1969.
There was no direct successor to the Mark 2 series. The 3.8 litre Jaguar S-type,
an upscaled and refined version of the Mark 2, had already appeared in
1963, well before the first of the Mark 2 models was discontinued. The Jaguar 420,
a more powerful and refined version of the S-Type, appeared in 1966.
Both of those models remained in production until late 1968, when the Jaguar XJ6 appeared, ostensibly replacing and placed rather midway between them and the larger, more expensive Jaguar Mark X produced since 1961.