It's not a full Skill Test but an LST.
No wonder there is so much confusion!
There is a PPL Skill Test for initial Issue and there is a Licensing Skill Test for renewal, both are FULL skill tests, they are just different and should not be confused. The Initial licence issue test is not repeated.
The LST is the same as an LPC; the only difference being its called an LST if the rating has expired and a LPC if its still valid.