You're right to wince a bit, if you have to mention it straight off the bat. But, it's never as bad as you think....

Doesn't matter what it is....

But, if there is some massive big fat non-negotiable condition you need met for you to accept an offer, then mention it right at the beginning.

You will only do 2 days in the office - mention it 

You actually need £10,000 more than was advertised - mention it

You have a driving ban until Sept 25 - mention it

Your veganism will preclude you from tasting the red meat you will be selling in this role - mention it

You need a company car and won't take a car allowance - mention it

Mention the elephant at the beginning of any application, and everyone shrugs - conversation might end. But, there's no drama - the emotional investment is low at this point, so really you can say what you need to without any aggy expectations being trampled by your elephant.

But, more to the point - get these non-negotiables out at the begin of the process and you have much longer to close your employer on your terms...

You wait till the end of a process... or even worse... till after an offer has been made... only to mention that you actually don't live in London and anymore and will be travelling down each week from Telford and need an extra £10K in salary to cover the commuting costs of your vintage lambo... 

Well, now your elephant has bolted, it's eating through your contract and crapping all over the desk of the over-stretched talent manager who assured the Sales Director that this 'deal was a dead cert'.

So, don't be that guy...

Just get the elephants out on the table with your CV straight away on the first call. 

And then smile, and tell them why you're worth it... rest is up to you...