Help! Concert dress

[Viewofthehills]

DD has to suddenly be in a concert tonight playing the piano after winning her class in a competition earlier in the week.
In a panic; all her dresses are too short, mine are too big for her.
Please, what should she be wearing?
Heading into town now- to make it worse, she can't come with me!

How old is she? And how formal is the concert?
My DD is 15 and teenagers round here don't dress up much when they're playing in concerts.

She's also 15 and it is formal. Men have to wear DJ's.
Think I'm off to Monsoon. Thanks for replying.

Usually it's a long black dress for girls in the concerts here. No need for sleeves though. If you don't get any in Monsoon, oddly BHS might have some.

Check out the black t shirt dresses in New Look and Top Shop. Both styles are round neck and long maxi length. New look £15 and Tops Shop about £24.

Whenever Dd1 (also 15) has performed in a formal concert, its allowed long black skirts/dresses or black trousers.
She has worn smart black trousers (M&S, Next.) and if its all black, a black camisole with short sleeved cardi on top.

We have found that for dd s long black concert dresses tesco have some surprisingly good ones

What did you get in the end?

I bought a dress from Monsoon, didn't fit. Cue slight meltdown.
I was about to sew her into my (too big) black dress when I remembered a dress I haven't worn for a few years which is a bit tight on me and perfect on her. Panic over. She looked gorgeous and played very well.

I'm going to check out all your suggestions though. I never want to be in the situation again where we don't know what she's going to wear up to an hour before a concert. I have been so stressed!

Thank you!