Ok then .. all our theories are only guess work but perhaps mine are wide of the mark. 729 would have been ideal for a test from New Ross though, as the frequency had probably only just been vacated by ABC .. if that is actually the case.

With regards to LASER 730 being on the side of the ship, I have never seen a photo of that but if anyone can provide a link??

As the original intention was allegedly for two stations to operate from the ship, maybe 729 was one frequency and 558 the other. By the time The Communicator had arrived over here from the US, the second service had been abandoned, hence the choice of either channel.

Interference on 729 would have been a two way issue with problems caused both to and from Laser in the London area, so I guess the decision to go with 558 was the obvious outcome.

Finally, it would make good sense not to use 558 for the earlier balloon tests from the Northsea as the delay in occupying the frequency afterwards, whilst the aerial masts were constructed, could have lost them the clear channel to either Caroline or the BBC / IBA.