@Predseda - I always thought it a shame that Braybrook never seems to have gave any interviews about the games he'd had a hand in back in the days of the Amiga. Everything that had his name to it always seemed brilliantly executed and I'd love to hear what he thinks about them now looking back.
@Akira - I wouldn't hold out much hope if it's a case of a bonus message/level. I only got as far as I did because I played from fleet one and over the duration of the session accumulated a ludicrous number of extra lives. But you never know - maybe with a bit more practice I can get a bit of the old grace back when playing the game but at the moment the first few fleets are fine then it quickly degenerates into a manta + wall explosionfest :q
Out of curiosity I had a look at one of the long plays of the game on youtube and it turns out it was the last fleet and I've noticed a couple of other spots on the last fleet of dreadnoughts where it looks like more keys may reside.