I suspect there is no answer to that question. The reason I say that is because it would appear that although passengers sailing from Queenstown generally seem to have paid above £7; with many of the English passengers at Southampton paying £8.1/- that many of the 'Continental' passengers paid amounts such as £7.17.11 and £9.10/- ; with some of those at Cherbourg paying figures such as £7.4.7
I have seen an advertisement for Titanic's Maiden Voyage which gives the fare from Southampton, London or Liverpool as £7.9/- and the fare from Queenstown as £6.10/-
Below I'm pasting 'Advertised Fares' for the return maiden voyage. which as with the above [Southampton, London or Liverpool fare] suggest 'package deals' for 3rd Class to/from places that were widely separated; and which will therefore have included inland rail or cross-channel/North Sea transportation. - It has been suggested [I would guess on the basis of those fares] that the 'Ocean Rate' for some 3rd Class passengers was as low as £3. - Otherwise as with 2nd Class [except for the outside rooms on D-deck] I would not expect any variation in the per adult berth rate fare.
Not necessarily. That is the point I was trying to convey to you.
The Maiden Voyage figure of £7.9/- I gave from an advertisement was for passengers from London, Southampton or Liverpool. If passengers travelling from London and Liverpool paid the same fare as those from Southampton then either they had free Rail Travel, or were paying a lesser rate for the "Ocean Rate" segment of the Total Fare Paid. - We know from 2nd Class Fare booklets that the 3rd Class Rail Fare from London to Southampton was 6/-
For the Return Maiden Voyage it would seem that whether passengers ended their journey at Plymouth or Glasgow they paid the same $36.25 = £7.5/-
Why Cherbourg should be so much more expensive is a mystery since the ship called there before Southampton. The same with Amsterdam being more expensive than say Sweden. - I find those fares difficult to understand; and can only say that while there is some evidence for a per adult berth rate of about £8; other evidences suggest that many paid a much lower "Ocean Rate". - Here I am trying to distinguish between the total fare a passenger paid and what they paid for the "ocean section' of their fare.
With 1st Class £26 was the Minimum fare from Southampton, Cherbourg or Queenstown; but the Minimum fare from London was £26.11/- [the 11/- being the rail fare from London to Southampton]; and from Paris was £27.15/- [or £27.14.3 depending on which Fare Rate booklet I look at]; with the £1.15/- [or £1.14.3] being the Rail Fare from Paris to Cherbourg.
We know the 3rd Class Rail fares from London [6/-] and Paris [15/11]; but what was the cost of travel from say Sweden to Southampton?
Looking at Sigurd Moen we know he paid £7.13/- of that 18/7 was "Forwarding" [which I understand in the case of 1st Class to be Rail Fares, but which with 3rd Class will likely include the cost of getting from Sweden to Southampton. There is also a "Board" figure of 7/6 [which could be some of the cost of getting to Southampton?] So the Nett Passage Money shows as £5.10.11 [it was £6.6.11; but that figure has been crossed out; because of the 16/- showing in a column headed "Supplementary Refunds" - and before you ask sorry I have no idea what that was for]. I believe that £5.10.11 was the "Ocean Rate". So Moen paid less than £8.
Kanio Ivanoff [from Bulgaria] paid £7.17.11 less 14/10 [Commission]; 8/5 [Forwarding] and 16/6 [Board] to give Nett Passage Money of £5.18.2. Again less than £8.
Mansour Hanna [from Syria] paid £7.4.7 less 12/- [Commission] to give Nett Passage Money of £6.12.7
On the other hand Frederick Ware [an English passenger] paid £8.1/- less 6/- [Commission] and 6/- [Forwarding] to give Nett Passenger Money of £7.9/-
So what was the 3rd Class Fare? - I suspect we should look at the Nett Passage Money figure; not at what a passenger paid in total.