Jane Merrick: Keep spending Sam. Keynes would approve

What was the most surprising thing about Samantha Cameron's sleek "modern Italian" kitchen, revealed for the first time in pictures showing her chatting to Michelle Obama last week?

It was not the complete box set of Brideshead Revisited, nor the impressive range of coffee table hardbacks on fashionable "rubbed black" shelves: Conran's Essential House Book, Provence Interiors, The Flavour Thesaurus, Paris Interiors. It wasn't the £200 Gaggia Coffee Maker, the £199 four-slot Dualit toaster or the his and hers iPads at £399 each.

Just as we take more notice of notes that are out of tune, with the Camerons it is the images that go against, rather than with, type that grab our attention. So, their decision to take a no-frills Ryanair flight at Easter was jarring – even if their luggage was top-of-the-range Longchamp.

But we expect to see Sam Cam perched on a £2,450 La Fibule sofa, in a photograph that could have come from the pages of House and Garden or World of Interiors. Just as we can imagine David Cameron, teddy bear on lap, enjoying end-to-end episodes of Brideshead. Even the scorch-mark on the cream oven glove was classic Cameron: the "Dad at Waitrose" cooking slow-roast pork while juggling the demands of office.

The surprising thing is that the millionaire Downing Street couple have spent so much on a kitchen – reportedly £28,000 in total – they may spend only five years enjoying. No 10 insist that the kitchen re-fit was all their own expenditure, and that taxpayers' money was spent on annual and necessary maintenance to the Prime Minister's offices elsewhere in Downing Street.

In 2015 or 2020, the Camerons can take the coffee table books and Magimix food processors with them, but not the dark grey cupboards, Corian worktops and £3,400 six-burner range cooker. Shouldn't we be horrified at such extravagance when the Prime Minister tells us to tighten our belts because "we are all in this together"? Who else can afford to spend nearly £30,000 on a kitchen that might not be theirs in a few years, and cannot even make them a profit when they leave?

Yes, we should question the expenditure of taxpayers' cash on refurbishing Downing Street, but where the Camerons have spent their own money, we should applaud them. The worst thing that the rich can do in a period of sluggish economic growth is to squirrel away their money in long-term investments and trust funds.

Her husband may not be a Keynesian, but Mrs Cameron certainly needs to be.

Of course, as the châtelaine of Downing Street, Mrs Cameron shouldn't flaunt her wealth or shove it down our throats when the rest of us are horrified that the price of broccoli has doubled since she got the measuring tape out in the flat above No 11.

But the mini-break Ryanair flight was so disingenuous, so staged, because the Camerons would never have put up with the no-frills boarding bun-fight at Stansted if they weren't in the public eye.

It was, similarly, a preposterous suggestion that the Prime Minister shouldn't wear tails to the royal wedding for fear of looking too grand in austere times – I can't think of a posher occasion to save them for.

I imagine Samantha Cameron receives a lot of her designer clothes free, or at a discount, but I hope she spent the full £895 on her white Jonathan Saunders dress for the No 10 barbecue, and the £2,435 for the Peter Pilotto silk floral number she wore when showing Mrs Obama around her new kitchen.

Don't scrimp on the steel pans, Sam Cam – your country needs your quantitative easing of the kitchen interiors market to stimulate economic growth.