Sometimes it depends on how far the employers head is not too far up their bums. What you should try to do is to build up a history with contact details - but that is also of limited value as folks move on and change numbers.
What they are looking for is some kind of 'trusted authority' - so your current boss is the main one. However, they should look more at your assessment of your skills and relevant abilities and qualificastions.
Then they should call you in for a chat and interview you. Then if they don't think you suck, they can give you a trial period during which you must prove yourself.
Don't over-think it.
Most stuff can be done with the GUI. You just say that's how YOU do it, and if they wanna find out another way they can just do a search for themselves.