Hello,
Rolf it is hard to say weather cabins A1 to A4 were occupied or empty. There are almost 60 (or at least over 50) first class passengers who's cabins or even decks we don't know. There is plenty of room to think that any or all those cabins were occupied.
A2 was occupied, however the photo was taken in Southampton, so I don't know whether Molson had yet moved from C30 to A2 by that time, it is likely, but like I said, I don't know.
Also I have my speculations that Sloper may have been in A4, however I have too little to prove it. I know he was on A deck and not far from Ross, and don't forget that McCaffry and Beattie moved from C6 to cabins on A deck close to Ross'.
As for the Odell speculation of occupying B deck suites, it was me who proposed it. I believe the ET cabin list has an explanation.
Now I personally think it's ridiculous for even ‘one-nighters’ not to be given a cabin. Of course Browne, Odells/Mays and Nichols were given a cabin. No ship let alone Titanic would leave a passenger without a cabin just because they only stay for one night. It is only commonsense that they did occupy cabins.
Just for the sake of explanation, imagine hotels let out rooms for a period of 7 days. Also lets imagine that 99% of the customers booked the rooms in that way. The rooms would cost say $1000 for that duration of time. If you were a customer that wanted a room for one night, why would you be denied a room just because you only want it for one night and were not prepared to pay $1000? Or imagine you wanted a hotel room for one night but were denied it simply because you were only a one night customer and were not prepared to pay 3 times the cost of the room for that!?
There was no need for Southampton - Cherbourg passengers to have a cabin. That is clear as they would only spend some 5 or so hours on the ship.
60 pounds for a cabin like A1 and A2 seems far too high, I don't know when or where Roberts/Madill/Allen booked their tickets, but it seems that Titanic's sailing was during an off season. Some booked cabins for as low as 25 punds 11 shillings.
Southampton - Queenstown cabin allocations may have had a similar history to that of "Complimentary" bookings. Andrews, Parr, Chisholm, Reuchlin were all booked "Complementarily". Thus they are not given cabins on the Cave list. There are other names on the cabin list with no cabins, but they either requested for their cabin not to be mentioned or they simply bought a ticket to sail on Titanic and have not yet been given a specific cabin.
Anyway, what I was trying to say with complementary tickets is they were free, thus cabins to persons bearing such tickets would be assigned at the last point, when all paying customers have reserved cabins to their likings. Once that was done and Parlor suite B52 had endured its numerous cancellations and no one else had reserved the suite by the evening of April 9, the suite was given to Ismay. Why not, no one else had paid for it. A36 would have been pricey, and being new it was unreserved thus the WSL was able to issue it to Andrews. I have no doubt that Chisholm, Parr and Reuchlin all received nice cabins, large. Possibly C deck or B deck suites or who knows maybe even A35, A3 or A4.
Thus since S - Q passage was a fare of 4 pounds, and various suites and large comfy cabins remained unreserved, why not give the 'one-nighters' a taste of what White Star Line cabins can be like and possibly attract them for further business in the future. To me it does not seem unusual that passengers joining the ship for one night only and paying 4 pounds can occupy such cabins as A37 and B72-74-76.
Daniel.