Can you send final reminder when no other has been sent?

We are a building company and have had an invoice from a sub-contractor claiming he did work for us in July 2012 however we did not receive his invoice until 22nd March 2013 (8 months after the date he is claiming to have worked for us!) We have explained we have no record of him working for us on this date as it was some time ago, yet they have sent us a 7 days’ notice of court proceedings, with no formal reminders before this other than a short email.
My question are they allowed to send notice before legal action when no other formal notice has been received? And also are we liable for paying an invoice for something that has been invoiced 8 months later, and if we are unable to find record of?

Benny wrote:

...And also are we liable for paying an invoice for something that has been invoiced 8 months later, and if we are unable to find record of?

Benny Boy, your business is liable up to 6 years from when the contract was made IF the debt is provable of-course.

Try and talk to the sub-contractor to ascertain evidence of the underlying contract (even if it was a non-recorded verbal contract) and of the work done. If there's no response to your phone calls, put your questions in writing. In this way, if your sub-contractor puts a claim in, then you can show the court that you have made every attempt to determine whether there is a liability on your behalf or not.

Best Regards