“An absolutely exquisite evening”, as Joyce Grenfell might have said, had she been at Shrewsbury's Theatre Severn last night. “Mrs. Knight had me off to a 'T'.”

Joyce Grenfell was one of the brightest stars in the light entertainment firmament in the last century. She also did the hard yards with ENSA in the desert war and sat on the revolutionary Pilkington Committee on the future of Television. She is most fondly remembered as a humorist and has never really been away. You can't switch on Talking Pictures without seeing her galumping about at St. Trinian's, or watch BBC 4 without catching an episode of Face The Music, with Joyce as a panellist.

Maureen Lipman boosted her legacy a quarter of a century ago with her own stage show Rejoyce - although the video suggests that performance was more Lipman than Grenfell. Cheryl Knight's stage portrayal of the National Treasure, however, is the real deal. She's been 'doing her' since 2010, and it's clearly a labour of love.

There are several old hats in this show but Joyce Grenfell is not one of them. Her material is 'of its time', certainly; but some things never change. There is still a naughty George in every Nursery, being told 'don't do that', and people still worry themselves sick about silly things. So amidst the laughter of nostalgia (and there was a lot of that) there were sharper observations about the unchanging nature of small scale humanity.

Cheryl Knight has plenty of silly stuff to go at. But her show of songs, sketches and letters also pauses for pathos. A woman can be 'torn in two' by her love for her beau and her duty to her ageing father as much today as in the 60s - with much the same conclusion. Grenfell's script for Telephone Call is heart-wrenching, Cheryl Knight's delivery is silencing and Paul Knight's gentle piano break underpins the mood beautifully.

But if you are looking for fun and laughter, you'll find plenty. For example, The School Reunion looks slight on the page but Grenfell has laced it with secret guffaws that only emerge when spoken. The repetition of Lumpy Latimer is given so many differing treatments by Cheryl, each is rewarded by an escalating wall of laughter. It's all very clever.

Cheryl is a little less haughty than Joyce, but even more expressive. There are knowing glances, subtle inflections, and repeated use of the 'Royal We'. We are watching posh kindliness at it's best. And we learn more about Joyce Grenfell than her screen and stage persona ever revealed. It's an intimate, feel-good experience.

Three stars

Reviewed by Chris Eldon Lee at Theatre Severn, Shrewsbury, on Sunday 17 May