How are interactions with professors on postgraduate open days taken into account in admissions decisions? I am applying for a masters in the UK and I attended an open day where I met various professors. I met with a professor who also happened to be the postgraduate admissions tutor. We spoke for a while and we really clicked and got on really well. We email each other and he has given me his thoughts on my suitability. He  identified areas of concern but he said he may be able to make me an offer.  It has become really clear to him that I am really passionate and enthusiastic. 

When he is looking through the applications and he comes across mine, will he take into account how much we clicked and how we met on the open day? 
Is he allowed to take into account things about me outside of my on-line application? Or is that unfair?
Objective criteria (such as grades, test scores) are often used to make the "first cut" of candidates. At the second and final rounds,  admissions decisions are made holistically and subjectively. 1 It is there that your being proactive and going to the Open Day, talking to professors, and the postgrad admissions tutor become things that  count in your favor. 

How much they will count is uncertain and unknowable. Ultimately it is your suitability to the program that is most important.

1. In the United States, the use of objective criteria such as race  has been cause for lawsuits and scrutiny by the Supreme Court.