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The dated British-English adjective Mrs Dale-ish means: conventionally middle-class.
This adjective is from Mrs Dale, the name of a conventional middle-class woman in Mrs Dale’s Diary, a BBC radio serial broadcast from 1948 to 1969.
The following explanations are from Mrs Dale’s Diary, published by the BBC:
[This radio serial] chronicled the lives of Dr Jim Dale and his family and friends, as told by his wife Mary. The Dales live in Parkwood Hill—a fictional middle-class London suburb.
[…]
Each episode began with Mrs Dale setting the scene as she spoke aloud, writing her daily entry into her diary.
These are, in chronological order, the earliest occurrences of the adjective Mrs Dale-ish that I have found:
1-: From Scottish District News, published in The Scotsman (Edinburgh, Midlothian, Scotland) of Friday 30th October 1953 [page 5, column 3]:
N.B. DRAMATIC CLUB.—The North British Dramatic Club’s presentation of “Black Chiffon” in the Little Theatre, Edinburgh, last night was attractively staged, but suffered from the usual defects which occur when a Scottish amateur cast put on what is essentially a Metropolitan play. The only person really at home with her part was Jennie Murray, the Scots nanny. Margaret Totty as the mother—the central figure of the piece—was rather Mrs Dale-ish, and failed—at least in the early part of the play—to give the impression of being under any sort of emotional strain. Tom Murray as the father was able to convey to the audience why life in the home was intolerable, but his actions were distinctly wooden. Rita Smith as Louise was rather sweet and kittenish, and Irene Smith as Thea, the married sister, gave an even and creditable performance. The play was produced by Stanley Holmes. It will be repeated to-night and to-morrow night.
2-: From Chance to See Lyons Feed, by James Thomas, published in the News Chronicle (London, England) of Friday 12th February 1954 [page 6, column 4]:
Life with the Lyons is a thoughtful affair these days. […]
The family have the lion’s share of radio popularity. […]
Now they have decided to give some extracts from their first family feature film […]. The date is April 2. […]
Ironically, the Lyons appear on the same night as a new domestic family series, as yet untitled or uncast, for which TV would have dearly liked—the Lyons.
As it is a TV spokesman said: “It will be Mrs. Dale-ish, more diary than comedy.”
3-: From a review of Call It a Day, a comedy by the British playwright and novelist Dodie Smith (1896-1990), performed by the Hartfield Players—review published in the Kent & Sussex Courier (Tunbridge Wells, Kent, England) of Friday 26th November 1954 [page 11, column 6]:
Most of the acting was good. Marjorie Marchant made a perfect mother-of-a-grown-up-family, being neither too subdued nor too Mrs. Dale-ish.
4-: From a disc review by John Mitchell, published in the Sunday Sun (Newcastle-upon-Tyne, Northumberland, England) of Sunday 12th October 1958 [page 4, column 7]:
Argo’s latest venture with the spoken word is an Alice in Wonderland on two discs […].
[…]
The story-teller, Margaretta Scott, sounds a bit too Mrs. Dale-ish for my own taste. And by side three she has developed a nasty head cold, poor girl.
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