A wide range of commemorative coins are being struck - from the rare kilo coin to the £5 silver which will be more readily available.
The two arrived late after their helicopter was forced to make an emergency landing minutes after taking off from central London.
Tributes have been paid to Princess Lilian, both in Scandinavia and in Swansea where she was born, after her death at the age of 97.
Prince Charles said he has "nothing but the happiest and fondest memories" of Nelson Mandela and that the world "will be a poorer place without him".
The Prince of Wales smiled as he recalled meeting Mandela in South Africa with the Spice Girls, which he said was "very enjoyable".
"We owe him an enormous debt of gratitude for what he's managed to achieve in his life", he added.
The Prince of Wales has guest edited Country Life to celebrate his 65th birthday tomorrow.
Charles's birthday falls on the eve of the start of the Commonwealth Heads of Government Meeting (Chogm) he will host in Sri Lanka.
It will be one of his most significant duties to date as a future monarch but the summit has been overshadowed with controversy over the country's human rights record.
He used his editorial to voice his support for farmers, saying they were not getting paid enough by big supermarkets. He said:
"It cannot be right that a typical hill farmer earns just £12,500, with some surviving on as little as £8,000 a year, whilst the big retailers and their shareholders do so much better out of the deal, having taken none of the risk."
Prince George has been given a Welsh gift - a tree planted in his honour.
Prince William will be given a certificate today by First Minister Carwyn Jones later to mark the gift which will be planted in Llyn Geirionydd near Llanrwst.
A tree has been planted for every child born or adopted since 2007 but one has been planted for Prince George because of his parents time spent living on Anglesey.
The world's media has been focused on the christening of Prince George today. As King, he'll one day be Supreme Governor of the Church of England. But in Wales, christenings are becoming less popular, with the amount of services almost halving in the last 20 years. Alexandra Lodge reports.
Prince George has arrived - being carried by his father Prince William - for his christening at St James's Palace.
The Royal Mint in Llantrisant has produced a special set of coins to mark Prince George's christening.
This is the first time that new UK coins have been produced to mark the christening of a member of the royal family.
A limited edition gold kilo coin has gone on sale for £50,000 but there is a more affordable range of gold or silver coins for £13.
The Duke and Duchess of Cambridge's son Prince George will be christened later in front of close family and friends of his parents.
The three-month-old baby, who will one day be king, will be baptised by the Archbishop of Canterbury, the Most Rev Justin Welby, in the little known Chapel Royal at St James's Palace this afternoon.
The Queen and Duke of Edinburgh are expected to be at the ceremony along with the Prince of Wales, who has become a grandfather for the first time, the Duchess of Cornwall and Prince Harry.
Kate's family - parents Carole and Michael Middleton and siblings Pippa and James - are thought to be invited, along with the godparents who, like the guests, have not been publicly named.