I have been in this situation already.
Passed my interview May 2013
Passed Conductor Assesment June 2013 and was told that I was 'on hold following successful Conductor Assesment'.
Received email in September nforming me that the Traincrew Plan had changed so no vacancies were available for the rest of 2013, so I was to be placed in the Talent Pool.
December 2013: Invited for second interview in Leeds on 9th January 2014
January 2014: Received a call to say I had passed my interview and that I will be receiving an information pack throught the post, then when a position becomes available I will be asked to attend a medical and then start on a course.
The Conductor assesment results are valid for Five Years and your interview score for Six Months.
So basically, you are on hold for any positions that come up at your chosen depot in the next six months and given the fact that there is going to be alot of recruitment this coming year, I would assume that you could well be in with a good chance of getting somwhere.
It has been hell for me waiting this long and you may not be waiting as long, but I assure you that it is well worth the wait.
Good Luck!!