''PS. I wouldn't do it for as little as 120K!
Hmm, sounds like the old tanker nickname "gravy boat" might come back into use..... '''
Line captains in some airlines can earn more than 120K (GBP) PA. TIREs will get more than this. Check some of the contract sites for an idea. Widebody TIREs can easily make US$20K a month. That's the going rate for the job - and you also have to take into account UK tax and all the BS which will go with the FTRS.
I too (out of curiosity - wasn't interested in the job) asked about the CoS. All I got was an offer to apply on line for the position. They're hiding something!