Padi, small historical research for you:
1. There is only one source of information (one author and one book) about Thornycroft DCTs on board of Grom class just after building and shortly after WWII beginning, so it may not be true. Even then it's true amount of available DCs for DCTs shouldn't exceed 10 (max 20) DCs, similar to Wicher class (20 BH 200 for racks and 10 for throwers). IMHO better to legitimate that there were not any DCTs onboard of Grom class, up to ORP Błyskawica overhaul started on 20.06.1941.
2. The single DCTs on Wicher class were most likely removed from these destroyers in 1934. After that in 1940 only ORP Burza was equipped with two Thornycroft DCTs and in 1942 with four Mk.IV DCTs.
3. I've found nowhere info about Thornycroft Mk.V throwers onboard of ORP Błyskawica and ORP Burza, so only Mk.IV version is verified.
Don't forget important info:
ORP Wicher and ORP Burza were both Wicher class, built in France. ORP Burza survived WWII, but ORP Wicher was sunk by German planes on 3 September 1939.
ORP Grom and ORP Błyskawica were both Grom class, built in UK. ORP Błyskawica survived WWII (she's still on the waves as museum-ship in Gdynia, Poland), but ORP Grom was sunk by German planes on 4 May 1940.
You gave me very interesting job with this, I wanna buy fresh released monography of all Polish destroyers using during WWII for making comprehensive research for you
