Address used for National Insurance Number application?

Hi guys, I have a work visa and am applying for a National Insurance Number. In the application form I have to list all the places I've lived in the last 2 years in the UK. They only asked me to provide my visa & passport so I suppose they'll double check my details with Home Office database.

The problem is that, when I applied for my first visa a long time ago, I filled in the application with an address I planned to move in. However, I had a dispute with the tenant there and left after just several days, before signing any contract. I vaguely knew the tenant from a friend and we lost contact since then. Now I even don't remember the house number! And of course I can't produce any proof to show that I've ever lived in that house.

I didn't report my new address to UKBA (don't know if we have to, actually none of my friends do). However, each time arriving in the UK (except the very first time) I always filled in the landing card with my new address.

What do you think about this? Will they check my past address? Thank you very much in advance!