The play's equine hero, Joey, made an appearance on the red carpet to greet guests such as Strictly Come Dancing's Craig Revel Horwood, Gloria Hunniford, Ulrika Jonsson and David Baddiel as it was announced the play would soon be moving to Berlin for the first time.
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Gavin and Stacey's Joanna Page told Hello! she was worried the tear-jerking play, combined with her pregnancy hormones, would have her sobbing uncontrollably.
The Welsh actress, who is keeping the name and sex of her first baby closely under wraps, said: "I've never seen the play before so I packed my bag full of tissues because i'm so worried i'm going to get upset, what with my hormones and everything.
"I also stuffed in a load of Kinder eggs to stop me feeling faint.
"My husband has been amazing at sorting out my pregnancy cravings.
"In the middle of the night I had a craving for Nandos chicken, it couldn't be any chicken in sauce, it had to be Nandos. So he drove for miles trying to get me one.
"And trying to find Cadbury's Creme Eggs when it's not Easter is pretty hard too, he's amazing. We're so excited."
Her co-star, James Corden, has taken to fatherhood like a duck to water. But Joanna says she is not taking any advice from him.
"Everyone has been trying to give me some advice but i've learnt to just ignore it and do my own thing otherwise I start panicking, so no. James is an amazing Dad but i'm going to do it my own way.
"I've been trying to get my dog on Gavin and Stacey for years but they won't let me. Hopefully they'll let me sneak my baby on instead in the next series."