/usr/lib/aspell/british-ise.alias is in aspell-en 2017.08.24-0-0.1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | # Generated with Aspell Dicts "proc" script version 0.60.4
add en_GB-ise.multi
|