In spite of such impeccable contacts, business is not booming for the company with the largest private stock of weapons in the Commonwealth, including 40,000 of Mr Kalashnikov's rifles. And Mr Kalashnikov confessed that times are hard for him, too.
Both have been speaking to Sam Cummings, president of Interarms (UK), a firm that is heir to old rifle company names like Whitworth and Colt.
Mr Cummings, 65 - born in Philadelphia, the City of Brotherly Love - founded Interarms in the early 1950s. It has traditionally done much of its business with the British and US defence ministries.
Interarms stopped buying rifles some months ago. Violence and horror abound, in Bosnia and elsewhere, but there is no shortage of weapons and prices are rock-bottom. Mr Cummings said the Serbs had made sure they inherited most of the former Yugoslavia's arms industry.
Mr Cummings said: 'The primary production points for all weapons - all lethal weapons - remain in Serbia in a physical sense. They make them at Kragojuvac, south of Belgrade. We're now banned from dealing.'
Croatia got 20,000 or 30,000 Kalashnikovs from Hungary, he said, but that was the only licensed deal to get through.
The business goes two ways. Until the United Nations embargo on imports and exports, Interarms imported hunting rifles from Serbia. Mr Cummings's warehouse is adorned with Soviet paintings, including a gift from the Tbilisi national museum. 'They kept the deliveries up right to the week when the embargo was imposed,' he said.
With the embargo on arms exports to crisis areas, eastern economies in dire straits and sharp contraction in armed forces, Mr Cummings said business had been flat. 'There's an avalanche of surplus from the whole eastern world, including China. We're afraid that next week it will be cheaper.'
The basic AK-47 Kalashnikov now sells for dollars 150 (pounds 79.78) a copy. The most advanced weapon in Mr Cummings' inventory, the Austrian AUG Steyr, sells for dollars 700 (pounds 372).
Mr Cummings said Mr Le Carre had been to Interarms several times. 'He said he wanted to sit around for about a week to get the atmosphere. One of the characters in his next book is an arms dealer operating from England. I said he was welcome to sit around but I could give him some work to do, too.'
Mr Cummings has been to the Kalashnikov home in Rzhevsk in Russia. 'Even he is complaining,' Mr Cummings said. He saw the two latest Kalashnikov designs last month. 'One resembles the Uzi (Israeli) - it's very compact, can be fired with one hand. The other is more foldable than the classic folding stock AK-74.'