Imagine if you will taking off from an enormously long runway and then finding that you simply cannot climb. All will be well until you meet or try to avoid the first obstacle.
Agreed entirely, if not able to climb out of ground effect. But the indications in this case are that they did climb well out of GE. They crashed over a mile further down.
For a Warrior (10m wingspan) to be in GE, they would need to be within ~ 10m of the surface. As I say, the indications are they they got a lot higher than that.
I don't know the wingspan of a Victor tanker but it's a helluva lot more than 10m, and it could thus fly in GE at quite a height.
As regards carb icing,
this (Southampton) suggests the air was quite dry. Probably not as hot as some suggest, either.