Showing Polly and the Prince by Carola Dunn

Polly Howard, an absentminded artist, is saved from a fall by a shabby
Russian vagabond. Kolya Volkov turns out to be a gentleman and a friend of her brother’s employer. Exiled from Russia, penniless, he must make his own way in England. He has nothing to offer her, and she, dedicated to her painting, doesn’t expect ever to marry—until a plot to blow up the Prince Regent’s Brighton Pavilion brings the unlikely pair together. Regency Romance by Carola Dunn; originally published by Walker