I have recently been involved assisting my son rent a flat in London. It was an interesting process where you would be given a 10 minute time slot to visit the property along with about another 30 other people and on leaving the building you were required to give your best and final rental offer on the spot to try and secure the rental. Obviously the rental price was getting driven up by this process, but you were also getting pushed to pay 6 or more months in advance to make your bid more attractive.
Simple fact is that over the last 40 or 50 years, UK population is bigger, divorce rates are up and life expectancy has increased and property building hasn't kept pace with increased demand which has driven up both purchase and rental prices.