change of employment

[pbs]

hello!
I am on tier 2 general visa. I was on same visa category with my previous employer later changed the employment and moved to London a year back. My previous employer is still keen to hire me back with a bit of pay rise. I really want o move back. my query is, does he have to go for labour market test? Also, currently I'm on post of accounts manager but my previous boss can offer me post of assistant accountant as he himself is chartered accountant. He won't be able to pay me as much as I'm earning currently but London is far more expensive than scotland so I guess I can convince UKBA on that matter. can anyone please advise me whether we need labour market test and whether this downgrading of my job post will have adverse effect?
Thanks in advance.