Incorrect Company Number

Hi,
We are buying a property where the Company Number of the registered proprietor has been incorrectly entered on the title.   This was only registered last year and so I am not sure why it was not picked up at that time (should it have been?),  However, the sellers will not correct this prior to exchange of contracts.
If I were to apply to correct this as part of my application to register the TR1 (which shows the correct Company Number, so does not match the title), how would I go about this and what evidence would be required, please ?

Hi Beth - if it's wrong then it can be 'picked up' at any time and amended. Use the contact form to 'report an error' if it has to be corrected before completion - Guidance and support for property professionals - GOV.UK 
If the seller is the company and they are coming off the register then confirmation re name and correct company number can be provided on submission - the key conveyancing QW is whether the buyer, their conveyancer and perhaps crucially any mortgage lender all accept and agree that the named company is one and the same of course
Companies House can confirm correct number and key with reporting an error is also to see whether there was a mistake in the submission/registration or not. Check the 'wrong number' via Co Hse as well to see if valid as well is something to help any decision-making