I'm in the middle of (trying to) move house, and our experience with HSBC has been nothing short of traumatic. I am warning anyone who will listen NOT to get a mortgage with HSBC.
Since the beginning of this year, HSBC have introduced a panel of solicitors who do their conveyancing work. The main one is Countrywide, who are now inundated with HSBC's cases and are clearly drowning. The buyer is still permitted to appoint their own solicitor, but everything they do has to be checked and approved by Countrywide... which takes forever. As an example, we sent our 'pre exchange pack' to Countrywide 6 days ago, which had been painstakingly put together by our solicitor to meet Countrywide's quite ridiculous checklist. Their stipulated turnaround time is 48 hours, but we have still heard nothing. Everyone in our chain is waiting for us, and the worst part is that NO ONE can help me - HSBC are even saying they can't contact Countrywide directly.
I won't go on about the details but the service is shocking - worse than anything I've ever experienced. There are other stories all over the internet/ complaints on Twitter etc. Until they change their policy, avoid them at all costs.