When the Frick Collection decided in around 2013 that the easiest way to obtain much-needed space would be to build a 60,000-square-foot addition in their Russell Page-designed garden, it must surely have known there would be an uproar from preservationists, landscape architects, the media, and their immediate neighbours on the Upper East Side.

Now things are calmer. This spring the Frick put forth a more modest expansion plan which, despite some serious opposition, made its way through the politically charged land-use-review process that includes input from the local community board and approval from the Landmarks Preservation Commission, a city government agency. (Crucial as the commission is, it’s not the end of the road for the Frick, which must face the city’s Board of Standards and Appeals – and more public hearings – on three requested waivers in September.)

But what can be learned from this expensive controversy that in some ways began decades ago, in the 1970s, when the Frick was forced to postpone an expansion for economic reasons? Since 1935, the Frick has added only 700 square feet of space, a minuscule amount, even as its collection has more than doubled in size and its attendance has ballooned, thanks to booming tourism. It needs space to serve its patrons, who are often left standing in long lines outside and then excessively crowded once they gained admittance. Similarly, the museum store and café are tiny and inadequate, and the office space dark and cramped.

One of New York’s loveliest buildings, designed by Carrère and Hastings and sited amid serene gardens, the Henry Clay Frick residence houses an extraordinary art collection that includes some of the most famous paintings on the planet: Hans Holbein’s Thomas More and Thomas Cromwell, grimly facing each other across the fireplace, just as Frick had placed them; a roomful of Jean-Honoré Fragonard’s Progress of Love panels; three gorgeous Vermeers, full-length Whistlers and Van Dycks, many Rembrandts, and much more. Although well endowed financially, the Frick is small by New York standards. Its smallness, long part of its charm, is becoming a burden.