Katherine put everyone at ease, treating all in the packed hall as friends and sharing some behind-the-scenes secrets about the Queen's 90th birthday show at which she sang, as well as family news of her pride and joy, 14-month-old daughter Aaliyah.
Backed by the excellent London Concert Orchestra, conducted by Antony Inglis, Katherine began the concert with Ode To Joy, before moving on to a spine-tingling version of Amazing Grace, then Sanctus and Angels From The Realms of Glory, with the audience invited to join in.
At ease: Katherine Jenkins
Special guest, tenor Jonathan Antoine of Britain's Got Talent fame, was introduced and proved he really does have talent with terrific renditions of Che Gelida Manina from La Boheme and Ave Maria.
Jonathan may look a little like Meat Loaf from 40 years ago but there was to be no Bat Out Of Hell tonight! Instead, the sacred songs prevailed as Katherine returned to the stage for How Great Thou Art and Silent Night before a medley of Welsh favourites, including Men of Harlech and Delilah.
The second half saw Katherine donning another figure-hugging frock for a sultry Santa Baby, complete with Marilyn Monroe-style wiggles!
It was soon back to more serious matters with the lovely Sleep Quietly My Jesus, followed by You'll Never Walk Alone from the musical Carousel in which Katherine will be starring in next year.
Sultry: Katherine Jenkins
While Katherine left to change into yet another new dress Jonathan Antoine returned for a show-stopping Hallelujah and perennial favourite Bring Him Home. A couple of jaunty polkas and waltzes by the orchestra heralded Katherine's return for O Holy Night and World in Union, then the house lights went up so the audience could find the carol sheets for a singalong of Oh Come All Ye Faithful and Hark the Herald Angels Sing.
There was just time for an encore of L'Amore Sei Tu (I Will Always Love You) and a well deserved standing ovation for a superb entertainer. I was even home in time for Katherine's TV Christmas special being screened on BBC1 so I was able to enjoy some of the music all over again!
Katherine concludes her 2016 UK Celebration tour at Nottingham's Royal Concert Hall on December 23 and London's Barbican Hall on December 27.