No - the fleet has to be dislodged to prevent it from convoying
i.e England has F Channel, A Bel, A Wales, France has F Brest, F MAO. England orders F Channel Convoy A Wales - Picardy, A Bel Supports A Wales-Picardy.
If France orders F Brest-Pic, F MAO-Channel, then the convoy succeeds, as the fleet in the channel is not dislodged (1 vs 1).
If either fleet supports the other into the Channel, then the Fleet is dislodged, so the convoy fails.
If England had a fleet in North Sea, that could support the Channel to hold, which would agian make the convoy succeed (2 vs 2)