There were one or two other and superior temples of Terpsichore-the Portland Rooms, generally known as " Mott's," from the proprietary, Mr. and Mrs. Mott, who had some connection with the ballet department of the Opera, and where, in consequence, one generally found some pretty members of the corps among the dancers. The rooms were in what was then called Foley Place - a broad thoroughfare opposite the chapel in Great Portland Street-the admission-fee was half a crown, and there was a fair five-shilling supper, served in an oddly-shaped low-ceilinged room like the cabin of a ship.

Edmund Yates, His Recollections and Experiences, 1885
[chapter on 1847-1852]

PORTLAND ROOMS, Foley-street, Portland-place. - Mr. H.C.FRERE begs to announce to the nobility and gentry his FULL-DRESS BALL will take place To-morrow Evening, Oct. 27, and every Wednesday and Friday during the present season. Tickets 2s. 6d. each. Dancing to commence at half-past 10. During the recess the rooms have been re-decorated and beautified.

Times, October 26, 1854

    Mott's, too, was a unique institution, select it might also be termed, considering the precautions that were taken regarding admittance. Every man who entered was known by name or sight. A man of good birth or position, no matter how great a roué, was admitted as it were by right, whilst parvenus, however wealthy, were turned empty away. It was told indeed that on one occasion, being importuned for admission by a wealthy hatter, old Freer, having been requested by the indignant shop-boy to take his card, had replied, "Not necessary, sir. Not necessary. I have your name in my hat." And so the line that divided the classes in the sixties was religiously respected. In those benighted days tradesmen sent in their bills apologetically, and if a tailor began to importune, a fresh order met the case. Flats were unbuilt, and people did not hear what was going on all and all night at their next door neighbour's; inferiors said "Sir" and "Right you are" was a phrase uncoined; if you dined at Simpson's or Limmer's you were served on silver, and no waiter ventured to ask you who won the 3.45 race; club waiters literally stalked one as they approached with a dish, and the caravanserais that now dominate the entire length of Piccadilly had not pulled down club averages nor reduced the prestige that attached to club membership. 
    ... The ladies who frequented Mott's, moreover, were not the tawdry make-believes that haunt the modern "Palaces," but actresses of note, who, if not Magdalenes, sympathised with them; girls of education and refinement who had succumbed to the blandishments of youthful lordlings; fair women here and there who had not yet developed into peeresses and progenitors of future legislators. Among them were "Skittles," [see below, ed.] celebrated for her ponies, and Sweet Nelly Fowler, the undisputed Queen of Beauty in those long-ago days. This beautiful girl had a natural perfume, so delicate, so universally admitted, that love-sick swains paid large sums for the privilege of having their handkerchiefs placed under the Goddess's pillow, and sweet Nelly pervaded - in the spirit, if not in the flesh - half the clubs and drawing-rooms of London.
    This remnant of old-fashioned homage was by no means unusual, and at fancy bazaars it was an almost invariable custom to secure the services of the belle of the hour  to sell strawberries at 2s 6d. apiece, which the fair vendor placed to her lips and then pushed between the swain's. 
    ... Situated in an unpretentious house in Foley Street, the ballroom at Mott's (as it appeared in the sixties) was a spacious octagon with a glass dome. At the side, approached by a few steps, was the supper room, where between 2 and 3 a.m. cold fowl and ham and champagne were discussed, the fiddlers descending from their loft, and revelry fast and furious took the place of the valse. 
    Not many years ago, impelled by an irresistible impulse, I visited the hall of dazzling light; a greasy drab opened the street door, and conducted me into a dingy apartment, which she assured me was the old haunt. Sure enough, there stood the dilapidated orchestra perch, and, yet a little way off, the steps that led to the supper room; and whilst I was contemplating them with something very like a lump in my throat, a squeaky voice addressed me, and I beheld a decrepit old man - all that was left of poor old Freer - whom memory associated with an expanse of white waistcoat, essaying hints such as, "Now, then, lady's chain," or hob-nobbing with some beauty, or remonstrating, "Really, my lord, these practical jokes cannot be permitted." This temple of the past may still be seen with all the windows smashed and on the eve of demolition.

'One of the Old Brigade' (Donald Shaw), London in the Sixties, 1908 

'Skittles'