Mail centre staff and network drivers are staging a 24-hour walkout, which will be swiftly followed by 78,000 delivery and collection staff staging a similar protest tomorrow (23 October)

However, Royal Mail has said that "its door is still open" to sign an agreement with the CWU, which it claimed was negotiated on Tuesday (20 October).

Mark Higson, managing director of Royal Mail, said: "My door is open and my phone is on and I am urging them again today to meet me so that we can all sign that agreement, get the strikes stopped and give us some peace in which we can get on with delivering Christmas for our customers.

"We have an agreement that was reached on Tuesday night and we had an agreement in 2007 - the real issue is not about getting agreements, it’s about the CWU leadership’s ability to deliver and honour them."

Earlier this week, Business secretary Lord Peter Mandelson warned that any prolonged strike action by Royal Mail members could force the Department for Health and NHS Trusts to look elsewhere for its delivery services.

He said: "I very much regret what is happening. Candidly, I think it is totally self-defeating for our postal services and those who work to deliver them."

But while the strike action has proved a headache for many businesses, other companies are benefiting from the current situation.

Dominic Duffy, managing director at Ceros, which provides an interactive online publication platform, said: "Publishers want to be seen to be doing something and we can help out, from a business sense.

"We're offering a service that helps publishers get over the postal strike, and we're handling many more titles specifically because of the strike. It has brought some new clients to our door."

For more, see Jo Francis' blog