Most shoppers looking for wallpaper or a few groceries are satisfied with a high street name. But Britain’s diplomats are more comfortable splashing out at George Osborne’s family firm or a placing an order with the royal emporium Fortnum & Mason, it appears.

An analysis by The Independent of spending by civil servants using Government-issued bank cards shows that the Foreign and Commonwealth Office has spent nearly £40m in the last three years – with the annual cost more than doubling from nearly £8m in 2010 to £18m last year.

The majority of the spending using the company plastic – known as Government Procurement Cards (GPC) – is to cover essential expenses such as hotel bills, but scrutiny of the thousands of transactions shows a range of additional spending – from taxpayer-funded pizzas to a kilometre of Union Flag bunting costing £2,500.

Among the companies to have benefited from the diplomatic shopping list in recent months is the high-end interior design company Osborne & Little, set up by Mr Osborne’s father and in which the Chancellor retains a 15 per cent stake worth an estimated £4m.

The list of the FCO’s procurement card spending for June reveals that it paid £1,298.95 to Osborne & Little for “fabric to re-cover chairs in Nairobi residence and wallpaper for Morning Room in Washington residence”.

Diplomats also spent £706.95 in July on unspecified goods from Fortnum’s. The spending lists also detail the cost and location of restaurant outings paid for using the cards, including a meal in July at a seafront restaurant in Brighton costing £838 and a visit to a trendy pizza outlet in central London costing £785.

Diplomats based in the Kenyan capital Nairobi also spent £1,951 in the River Cafe, a highly-rated restaurant situated in a garden centre, and those in Burma £539 at Dial-A-Curry, a restaurant in the capital, Rangoon.

While schmoozing – and the showcasing of British products – is arguably part of the diplomatic corp’s job, the use of procurement cards across Whitehall has come under increased scrutiny following criticism from MPs and the Government’s own auditors that spending was poorly controlled and potentially open to abuse.

Speaking last year, Margaret Hodge, the chairwoman of the Commons Public Accounts Committee, said: “The controls are not strict enough to deter and prevent inappropriate use.”

Figures released earlier this year showed £1.1bn was spent last year using the cards by 137,000 officials across central and local government.

Yesterday the FCO insisted that while it was unable to provide further details on individual transactions, the use of the cards was cost effective and it had measures in place to guard against inappropriate spending.

A spokesman said: “GPC is a flexible and straightforward method which allows the holders to purchase commodities in the most cost-efficient and timely way... All our spending is rigorously scrutinised to ensure it is appropriate and provides value for money for the taxpayer.”

Diplomatic swag: the FCO’s bill

July 2013 £706.95 (Fortnum & Mason Co); £838.97 (Al Fresco restaurant, Brighton); £785.51 (Pizza East, London); £1,027.26 (High Spirits Bar, Budapest).

June 2013 £1,298 (Osborne & Little – “Fabric to re-cover chairs in Nairobi residence and wallpaper for Morning Room in Washington residence”); £539 (Dial-A-Curry, Yangon).

May 2013 £898.97 (Summer uniforms for seven cleaners, Turkey); £1,107.50 (Opera tickets and rides on the London Eye for participants in the Future International Leaders programme

April 2013 £673.54 (“Hire of boat and crew for Governor [of Turks & Caicos Islands] to view reef damage”).

March 2013 £2,505.45 (“1km of cotton bunting plus storage bags for use at residence”).

Feb 2013 £1,057.16 (Gym equipment).

December 2012 £3,059 (Combined cost of “Official cinema event for advance screening of Skyfall” at three locations); £1,469.98 (New flags for Queen’s visit to the FCO).