"They went on holiday to France last year."

Translation: Ils sont allés en vacances en France l'an dernier.

[engyeomy12]

Instead of 'l'an dernier', can I use 'l'année dernière'? In fact, the latter seems to be more appropriate according to my french books. Are there any differences between these expressions? Please explain it the nuance of each sentence, SVP. Merci d'avance!

[Ripcurlgirl]

According to this website here you can. It states:

However, note that an/année is far more flexible than the other pairs; for "last year" you can say l'an dernier or l'année dernière, "next year" can be l'an prochain or l'année prochaine, etc.

And you will find them on WordRef here and here.

But you will find that even the French debate when each should be used here.