The Lady of the Lamps by Daphne Quinn

A broken vow. A broken soldier. A broken heart.

On her first ever visit to Vauxhall Gardens, Lady Beatrix Chichester is enchanted by the magical lights. She dances with a dashing young man who promises to call on her as soon as she’s officially out in society.
Five years later, one dead fiancé, and with offers of marriage from men old enough to be her grandfather, Lady Beatrix returns to the gardens, hoping they can make her feel some of the magic she felt back then, when everything seemed possible.
Spencer Clement, now the Marquess of Leighton, has returned from the war in France, physically whole but mentally scarred from the horrors he has witnessed. Vauxhall Gardens seem a world away from the battlefields he has been living in, but his friends persuade him to join them one night.
When he and Lady Beatrix end up dancing under the incredible light of a thousand lamps, he feels something for the first time in years—but then the fireworks begin and the horrors of the guns are at the forefront of his mind.

Will he ever find his lady of the lamps again? And will she be able and willing to fix this broken soldier?