I've had no issues for a visa. First time, don't come for 6 months. In the letter, she's visiting for 4 weeks or so. My wife had a terrible immigration history before, and I was extremely doubtful they would let her in. But it was super easy, barely an inconvenience. We were open aboout her immigration history, by presenting her old passport, which included the Malaysian Black Listing. The agent tried to get me to write flowery begging letter like some poor sap, who went into a detailed description how he met his wife, everytime he visited Thailand, met th family etc. I did none of that. Simple A4, stated my salary, enclose P60, copy of mortgage statement, purpose of visit, where she was staying and stating I would be responsible for all costs. She has a small business that makes sod all money, but I made sure she got it registered properly, and had a business bank account. She doesn't have a house, not even a rented place (lives in the shop), grown up daughter. They didn't care that she had no money as such. I have never shared photos, nor emails nor any other messages between us. Applications aren't considered by a British official; its outsourced to VFS in India, who process 3.2 million applications a year, 80% of tourist applications are granted, so that means 90,000 applications are made from Thailand each year. VFS are, overall, processing 6 applications per minute. They must use automation as part of the screening. I decided to make the introductory letter curt, concise and to the point, with no information that was unnecessary to the application. When your does go through UK passport control, she will be mildly grilled, such as asking her why she is here, first time in UK, where is she staying, very friendly, and they don't mind if she gets stuck. Hot tip, use the family line. Through super quick.