Buckingham Palace keeps a "little gold book" in which are the names of homeware and interiors specialists who can supply everything from a latter-day "cloth of gold" silk brocade — from Gainsborough Silks, the Suffolk weavers founded in 1903 — to an über-modern Perspex coffee table from Zone Creations, the Merton laser cutters.
What these specialists have in common is that they are all royal warrant holders who have supplied goods or services for at least five years to at least one of only three royal households — that of the Queen, the Duke of Edinburgh or the Prince of Wales.
There are about 800 royal warrant holders, an intriguingly diverse bunch. They range from purveyors of champagne and fine foods to retailers of suits, gloves, saddles, furniture and kitchen cabinets, to conservators, builders and decorators, hay and straw merchants, and technology specialists providing software and mobile phones.
About 160 are connected with interiors, from furnishings and appliances to maintenance services. And all are listed on the website of the Royal Warrant Holders Association (established 1840; RWHA; rwha.co. uk) for everyone to access and use.
The Duke and Duchess of Cambridge do not grant royal warrants — yet — but the Goring Hotel in Belgravia, where Kate spent her pre-wedding night in 2011, gained one from the Queen for "hospitality services" last year. Gainsborough Silks was asked to provide fabrics for its royal suite.
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The Coronation Festival
A one-off Coronation Festival will be held in the gardens of Buckingham Palace celebrating the work of warrant holders (July 11-14; coronationfestival.com). There'll be room settings, fashion shows and stands, with goods and services from 200 of the companies that have won the right to flaunt royal patronage in adverts and on packaging with the Royal Coats of Arms.
The Queen's is flanked by that familiar jaunty lion and unicorn; Prince Philip's is "supported" to the left by a nearly naked Hercules, while Prince Charles has the lovely feathers of the Prince of Wales.
The royal warrant holders are a fascinating resource for any Londoner who aspires to a beautiful home. Looking for a lamp shade maker or a glass engraver? The RWHA can oblige.
"Royal warrants are a mark of quality and service," said Richard Peck, RWHA secretary. "We have everyone from craftworkers, one-man bands and small family firms, to those big iconic British brands, industry leaders and huge multinationals."
On the royal roll call for fabrics are such big Chelsea Harbour brands as Warners, GP&J Baker, Jean Monro, Cole & Son and Turnell & Gigon.
Warrant holders are also at the forefront of technology. For example Brintons Carpets, a 230-year-old brand that first gained a warrant in 1958, is launching a new 32-colour "high-definition weave" with its Coronation range of rugs (rugs-bybrintons.co.uk).
The "eco-bedroom": sustainable design built to last
Business ethics and sustainability are as important as quality. Indeed Chelsea's KLC design school has created an "eco-bedroom" for the Coronation Festival, all made by warrant holders (pictured below).
"The eco-cred of raw materials is important," said Jenny Gibbs, head of KLC. "But sustainable design is also about making things that will last. The royal warrant holders do this really well and offer beautiful British craftsmanship from beds, furniture and mirrors, to lighting, curtains and floors."
Indeed, the RWHA has its own charity to nurture British crafts. The Queen Elizabeth Scholarship Trust — QEST — set up in 1991, has awarded £2 million to 300 craftspeople for study and training (qest.org.uk).
A three-hour behind-the-scenes tour of Mayfair warrant holders (including Paxton & Whitfield, Floris, Penhaligon, Berry Bros & Rudd, Garrard & Co and Fortnum & Mason) costs £365 plus VAT, for up to five people (londonluxuryquarter.com).
It's a question of royal patronage
Who are "drapers and furnishers" to Princes Philip and Charles?
Peter Jones, SW1; and the John Lewis in Reading (nearest branch to Windsor) are "suppliersof haberdashery and household goods".
Where does the Queen go for china and glass?
Thomas Goode of Mayfair has held a royal warrant since 1955 (020 7499 2823; thomasgoode.com).
Who refurbishes her chandeliers?
Wilkinson of Sittingbourne in Kent does glass restoration of all kinds, holding a warrant since 1986 (01795 830000; wilkinson-plc.com). Crystal Lite Chandeliers of Crews Hill is also an established warrant holder (020 8367 6766; chandeliersltd.com).
Who frames pictures for Prince Charles?
Rollo Whately, warrant holder since 2001, at 41 St James's Place, SW1 (020 7629 7861; rollowhately.com).
Who makes the Queen's coathangers?
H&L Russel of Laindon, Essex, has been making them for her since the Eighties (01268 889111; russel.co.uk) Find all 800 warrant holders listed at rwha.co.uk.