I\'ve learnt how to grep lines before and after the match and to grep the last match but I haven\'t discovered how to grep the last match
The approach I would take it to reverse the problem as it's easier to find the first match and print the context lines. Take the file:
$ cat file
foo
1
2
foo
3
4
foo
5
6
Say we want the last match of foo and the following to lines we could just reverse the file with tac, find the first match and n lines above using -Bn and stop using -m1. Then simple re-reverse the output with tac:
$ tac file | grep foo -B2 -m1 | tac
foo
5
6
Tools like tac and rev can make problems that seem difficult much easier.