Unregistered house sale, lost deeds, what's the time frame?

Hi there, 
We are in the process of buying a house that is not registered and the seller can't find the deeds. Their solicitor has just submitted the application to register the house.

If the application is expedited, what is the average time frame it takes to get the title?

As we've already waited 7 months in rented accommodation while they put the application together (we were led to believe it had gone in much earlier), we're worried how much longer the process might take. 

Many thanks for any insight.

Hi Nicole - it's very hard to be definitive re such things as there are a number of things to still happen re such cases. They need to submit, request expedition and then trust the supporting evidence is sufficient to pass the fist stage, namely consideration by a senior officer (2-3 weeks)
A site visit/survey is then needed (2 weeks) and the final stage is potentially notifications to adjoining landowners (3 weeks)
But rough timescales really depend on Stage 1 and what's then needed/next steps but there's no quick fix or expedite magic wand sadly.

Thank you Adam, this is really helpful, and thanks for such a prompt reply!