What type of operator, private/AOC, how long have you been with them.
Going out to market to get rated left seat guy with experience we are talking 120-150 in the UK, you will not get that if on an AOC, more like 90-120.
Now if you have been with them for a while and they are private, it all depends on what kind of money you are on now and you would need to negotiate, get one of those agencies to give you a quote for a typed, experienced Captain and use that as a bargaining tool.
It is a pilots's market for rated, experienced left seat guys on the Global, simple economics, not many around, especially in Europe.