RBS Aviation Capital, the plane leasing subsidiary of the Royal Bank of Scotland, has placed orders for Boeing and Airbus planes worth £5 billion at the Farnborough Airshow.

The orders include 52 Airbus A320s and 43 Boeing 737s, with delivery expected between now and 2015.

The company counts some of the world’s largest airlines as its clients, including Lufthansa, Qantas and Virgin Atlantic, as well as carriers in strong emerging markets such as South America and China.

The bumper deal was placed some time ago but deals in the industry are often not made public until a major air show.

RBS Aviation Capital chief executive Peter Barrett said the purchase reflected strong demand for leased aircraft, particularly in emerging markets in Asia, Latin America and the Middle East.

“We always buy when we think there is demand and sell when we see no demand from investors,” he said.

“It reflects the underlying long-term trend that there is demand for leased airplanes, particularly for the narrow-body ‘workhorses’ of the industry, the Airbus A320 and Boeing 737.”

Leased aircraft make up 35 per cent of the world’s aircraft fleet but that percentage is rising as airlines increasingly look to reduce their capital costs.

”I think airlines are optimistic but there is a suggestion of caution which also reflects the broader economy,” he said.

RBS, which is 84 percent-owned by the UK taxpayer, has been actively looking to divest its aviation business as part of an attempt to raise cash by selling non-core assets. However, these plans are currently on hold.