By Emma Mackenzie As the Royal Family faces a challenging period – with Kate and King Charles both off duty due to medical issues – it looks to potentially get even more controversial: with Kate’s ‘black sheep’ maternal uncle entering the Celebrity Big Brother house. Gary Goldsmith, 58, enjoyed his television debut last night and is known for his candour when it comes to discussing the royals, particularly Prince Harry. While Goldsmith speaks of the Princess in nothing less than glowing terms most of the time, his inability to hold back makes him likely both a great draw when it comes to telev…