So far as I am aware, this is the first time the following has been presented:
England: F(NTH) C FRENCH A(Bel)-Hol
France: A(Bel)-Hol
Russia: F(Den)-NTH,F(Hol) S F(Den)-NTH
Once again, in this example England would like to be dislodged - presumably to take a strategic retreat. Russia doesn’t care to risk Hol, so the support comes from there. France’s motives are not known. Perhaps he wants to thwart the dislodging of F(NTH); perhaps he wanted to cut another possible support which F(Hol) might give; perhaps he just wanted to move into Hol. At any rate, under Rule X, A(Bel)-Hol has indeed cut the Russian support. However, XII.5 says that a conveyed army’s attack does not cut support given to an attack on the convoying fleet - the attack does not "protect" the fleet and without that protection, the fleet is dislodged. The problem here is XII.5 and X are in conflict, and there is no place where the Rulebook says which is to take precedence. My own recommendation, as given above, is that the convoy rule takes precedence, and England be allowed, his crafty finesse of the attempted cut.