i use to watch this too at junior school in petersfield hampshire around 1975. the odd thing be that from time to time i still think about it ( i be now 40 ) the big question run through out the length of the series ( no idea how many episode 6 . ) be the identity of the person rid the motorcycle . i have ask friend in the past about this series and they have no idea what i be talk about and think it some kind of weird dream i have have . i have never understand to this day the educational benefit of this but think at the time it be great but slightly scary . i seem to remember that there use to be a break of some sort in the middle of each episode . no idea why . would love to see it again . get hold of a short clip via the bbc cult website .