Tested Seaward PrimeTest 100. On R_iso test it puts out about 605V DC, but with an initial spike up to 810V. It is the same with or without a 220 R load. On I_Leak it does 40V RMS, as specified.
Power on all test modes is applied between L and N together against earth.
IET PAT testing Code of Practice 5th ed. gives leakage limit of 5 mA. Note Hacklab PAT tester has a lower fail limit of (probably) 0.75 mA.