BOAC, even if they had all instruments available, I hardly doubt that they could have recovered, considering that they were in a "deep stall" (we don't know if they were). There are several instances of stall incidents that make me vary (KAL 747 near SFO, unconfirmed "test flights" described in this forum)
Without the instruments, I really wouldn't want to find out how a recovery works: When you push your nose down, when do you start to recover? If you pull too early, you stay stalled, if you pull too late, you end up in real overspeed. Rememember they didn't have airspeed all the time.