Seven? https://en.wikipedia.org/wiki/Wikipedia:Identifying_reliable_sources

Eight? https://en.wikipedia.org/wiki/Talk:British_heavy_tanks_of_World_War_I#Mark_V_series_use_in_Berlin_1945

Nine? Read your sources over and over and over again.

Ten? "It's not clear where they came from, or just what use was made of them." Apart from the fact that we do know where they came from (Smolensk - are you actually reading any of this?), I couldn't have put it better myself. There is consensus.

I think this sums it up very nicely:

"The last known use of the Mk V in battle was by units of the Red Army during the defence of Tallin against German forces in August 1941. The four Mk Vs previously operated by Estonia were used as dug-in fortifications. It is believed that they were subsequently scrapped."

"In 1945, Allied troops came across two badly damaged Mk V tanks in Berlin. Photographic evidence indicates that these were survivors of the Russian Civil War and had previously been displayed as a monument in Smolensk, Russia, before being brought to Berlin after the German invasion of the Soviet Union in 1941.[6] Accounts of their active involvement in the Battle of Berlin have not been verified."

Fletcher is wrong about the number of vehicles, but the facts about them can be established separately. Assumptions about them cannot. We can establish 1941, but not 1945.

(Btw, at Tallin two of the Estonian vehicles moved under their own power, and two were towed into position. Info not yet published, so that is FYI only. Don't put it on Wikipedia.)

I've referred before to your collection of runner-up medals. I don't know why you persist. We're in Roy Hodgson territory. I'd call it a day if I were you.