Many guest toilets are dismal places but John Rocha has bucked the trend, with a sparkler, writes Robert O'Byrne

HERE IS the origin of a certain unnecessarily coy euphemism. The German composer Max Reger once received a bad notice for one of his works and immediately sent the following response to the critic responsible: "I am sitting in the smallest room of my house. I have your review before me. Soon it will be behind me."

And that's how most of us view the average guest loo: a place to put behind us as quickly as possible. Too often the modern home's proverbial smallest room is also its most dismal, a glorified cupboard reeking of parsimony and ineffective air freshener.

Tucked under the stairs and with insufficient space even for tentative cat-swinging, it's either been the subject of minimal interest (that is, treated as a burial ground for old issues of Hello!) or else tricked out to look like a Lilliputian version of Versailles's Hall of Mirrors.

Whatever the decorative option, there's invariably an unwillingness to acknowledge the functionality of the place, the fact that it serves one specific purpose only and ought to be designed accordingly. Which is why it's so refreshing, in every sense of the term, to visit the guest loo of John and Odette Rocha. Of course, from the outset anyone visiting their Dublin home will know this is somewhere special. Standing at the end of a late 19th century terrace, the house was entirely revamped by the couple before they and their two children, Simone and Max, moved in 18 months ago.

The clean, spare lines of the front garden immediately announce a distinctive approach to design, as do the generous expanses of glass visible from the building's rear elevation.

The refurbishment was done to John Rocha's specifications, although he points out that two architects work in his design studio. "I knew what I was looking for," he says. "I'd my own ideas and then the team came and worked with me on it."

After buying the property, a year was spent following the planning process and then another two with builders on-site before the work met his demands. But the results more than justify this long time frame.

Internally the house is a comfortable and confident fusion of the old and the new.

Wherever possible, original features, such as elaborate cornices, were retained and restored. Sometimes this wasn't feasible, in which case rather than attempt to recreate what had been lost, John and his team opted for a contemporary approach. At the back of the building, for example, an extension was added in which glass predominates and this has the effect of introducing far more light than previously.

Providing an understated backdrop to the Rochas' collection of contemporary art and furniture, walls are uniformly white, floors invariably of stained wood, windows left undressed. A consistent aesthetic of restraint applies throughout.

Except, that is, for the guest loo - where an altogether different approach has been taken. First of all, unlike everywhere else, there's no natural light here; in this it conforms entirely to expectations. But not otherwise, because the way the designer has approached dealing with a modestly proportioned and functional space is anything but mundane. On the contrary, to visit the smallest room chez Rocha is akin to stepping into a gorgeous jewellery box.

All the walls are sheeted in black glass inspired, John says, by the collection of tableware he designed for Waterford Crystal. This is by no means Waterford's only contribution to the room. A floor-to-ceiling screen that conceals the loo from the entrance door is entirely composed of crystal chandelier drops arranged in a series of elaborate patterns. John worked out the design, his daughter Simone and two friends spent three days putting it together (with assistance from a special adhesive), and then the whole lot was pressed between two panes of clear glass and installed.

More pieces of crystal were used to make up the surrounds of the sink before the actual item was constructed from further panels of glass bonded together to avoid the risk of water leakage; above this hangs a plain but well-lit rectangular mirror. The floor is covered in slabs of polished black stone.

It's not fussy, but it's not understated either, not Versailles-on-a-budget and not a repository for magazines nobody wants to read. This is a room that, for all the modesty of its dimensions, packs a memorable punch - and also makes no attempt to conceal its practical function. "Yes, I think it works," says John modestly. Actually it works so fantastically that the loo has been recreated in an apartment he designed at Crosbie's Yard, Dublin 3, which is due to be auctioned on behalf of the Irish Hospice Foundation. Whoever buys that apartment should be prepared to find guests spending the greatest amount of time contentedly concealed within its smallest room.