Offsite Backup domain controller

My company,s PDC is in London. We are planning on setting up a BDC in Liverpool. There is a 56k kilostream line connecting London branch to Liverpool branch.
How do I set up a BDC in Liverpool that will recognise the PDC in London? I have tried everything. NO SUCCESS. ( I have added a new BDC name and IP address to the PDC in London through the server manager. I have manually added the IP address in WINS. STILL no success). WHAT AM I DOING WRONG!!!!!!!!!!!!