They are very good. How do I know? I used them this year as am in the same boat, Limited Company and high street lenders and standard indy mortgage brokers were next to useless. I applied through these guys and just needed signed contracts and they were then able to lend at 4X contract value. I did have to supply the usual bank statements (personal and ltd) plus the contracts and it was very painless from there. Beware some companies who want to charge an arrangement fee - these guys do it solely on their commission from the mortgage provider so was far cheaper.
