By Jon Robinson The success of Prince Harry’s best-selling memoir Spare helped drive sales at book publishing giant Random House, it has been revealed. The business, which is part of the Penguin Random House group, saw its turnover jump by 13.2 per cent to £262.3m in 2023, helped also by the Board of Lunch series which focuses on air fryer and slow cooker recipes. However, Random House’s pre-tax profit fell from £38.9m to £29.2m in the year mainly because a profit made on the sale of fixed assets of £13.9m in 2022 was not repeated in 2023. Random House issued a dividend of £75m during the year…