They had decided that he was living in an area that was not commensurate with his income.
very similar, i purchased my house at 40k when it valued up at 110k ( 2002 ), off my family as a present. one year on, First day they arrived with warrent, they listed every expensive item in my property, asked me were and when it was purchased, and checked it there and then. I was a property manager and they had mixed up my personal and business accounts, with a client account that had 250k pa going through it, All sorted out eventually.

I had made some slight filing errors, but i was honest with the tax man, from the start ( admited something inconsequential ). He told me how the fines systems works. If you dont withold anything at the first or subsequent meetings, and provide your full books/reciepts. you will generaly only be fined the same amount as any missing tax. ( as long as its a mistake and you have not tried to deceive them to badley ). Still it was 4 months of hell.