Some possible reasons for a delay of this length are:
1. Your solicitor is or was awaiting papers from the solicitor for the vendor. For example, the solicitor for the vendor would have redeemed the vendor's mortgage if there was one; Then they would have written to the legal department of the bank to get a release signed. Then they would have sent it to your solicitor; Then your solicitor would have registered it in the Land Registry or Registry of Deeds.
2. If it is a registered titile, the Land Registry - in particular the mapping section. If the property you bought was a single Folio, then registration can go through in a matter of weeks. However, if the property was part of a larger folio (for example, a site carved out of a housing estate) it can take anything from a few months to a few years for the papers to go through the Land Registry. In some counties, the Land Registry are currently goign through a process of converting to digital maps, and this has raised a whole new series of bottlenecks. It will be worth it in the end, but Land Registry Mapping is a serious cause of delay at the moment. Bear in mind that even if you bought a second hand house in a housing estate, it could still be affected by these delays, if the original purchaser was not yet registered on their own separate folio.
You can check progress online at the Land Registry, but you need an account with them, so it is not practical for a consumer. It it is a Land Registry title, your solicitor should be able to respond to your queries by sending you a printout from the Land Registry showing your Dealing Number (i.e. the Land Registry reference for processing your application) and its status.