i seem to remember doing a successful escape on the speccy version.
as i recall the trick was to leave the papers and whatever else you needed at the last stage (passport? i forget) close to the exit before actaully doing your break out, so you could drop the wirecutters / torch etc, grab your stuff and escape without recapture
i think i actually didi it emulating it on ZXAM.... damn it -was- a long time ago!
I tried to progress up to COlditz on the miggy, but that game was just too big! (so many locked doors leading to nothing!)