Are there any legal guidelines with regards to reviewing rental applications?

My partner and I viewed a property at 6.30pm on Tuesday along with several other couples and upon asking for rental application forms were encouraged to apply (that night) and were told we would find out Wednesday regardless of if we were successful or not. We took the time to send everything though that night and did not hear anything Wednesday. Thursday I phoned the agent to find he was now on holiday but spoke to a colleague expressing my dismay that he didn't get back to me and that I had hoped to get some feedback on our application. I was told that the property was let to a man who had faxed in his application before they had even viewed the property and that their policy was first in best dressed - therefore none of the other applications were even looked at. I had not heard of that practice before and said that did not seem very reasonable as why would anyone bother to put an application in on the day. I was told it was impossible to choose between for example five great applications so they just pick the first one they receive. I asked if the Landlord had any say in the matter and was told they had authorisation from the Landlord to choose the tenants and that this was the way they operate. Is this legal?