Deadlines and conundrums on Royal Mail's busiest day

They've seen it all at the Glasgow mail centre. Letters to Santa. Cards with just a name on them, that were never supposed to be posted. And letters with the most confusing, or incomplete, addresses.

The worst so far this December was posted, first class, over the weekend. It's addressed to: James Carrigan, My Best Mate, Stays in Cardonald, Glasgow.

Just one item out of the four and a half to five million cards and letters that postal workers at the mail centre will handle in one day - their busiest of the year.

Royal Mail is proud of its technology. Machines that read addresses. New systems that sort post down to the level of an individual postman or postwoman's round.

But machines can't cope with an address like that. Making sure that this card gets delivered will come down to human beings, with local knowledge and a determination that they won't be beaten.

Alan Gairns, collection and delivery director for Royal Mail in Scotland, told BBC radio's Good Morning Scotland programme he was confident they'd track down James Carrigan, wherever it is that he stays in Cardonald.

"Pretty good chance," he said. "Our people in Cardonald delivery office will do all they can to make sure that it arrives on time."

Alan Gairns from Royal Mail

And they can certainly point to success in the past.

This time two years ago Royal Mail staff were trying to deliver a card addressed to: "Mr Bill and Mrs Evelyn (sorry don't know the surname!), little house opposite Heylipol Church", and that one got delivered, to the right address on Tiree.

But, Alan Gairns says, if you want to give your Christmas post the best possible chance of getting through you should use post codes, and post early.

Though, he says, the business is pulling out all the stops too.

"In Royal Mail this Christmas we're investing an additional £15m to make sure that mail gets to the customers on time," he explains.

"We've got an additional four flights, and four trains, into and out of Scotland. We've got 2,000 additional seasonal workers. And we've got another 500 vans."

"But all of that is insignificant if we don't get the post code right."

Last posting dates for Christmas mail this year are: Saturday 17th December for second class post, and Tuesday 20th December for first class items.