A good post Uncle Doug
The Office for National Statistics data supports your contention that there has been a decline in visits to the UK:
There were 3.3 million visits to the UK by overseas residents in April 2018 (11% fewer than in April 2017), 3.5 million visits in May 2018 (3% fewer than in May 2017) and 3.2 million visits in June 2018 (9% fewer than in June 2017).
There were falls in the number of visits compared with a year earlier, but it should be noted that visitor numbers were the highest ever recorded by the survey in the corresponding three-month period of 2017.
Overseas residents spent £1.8 billion on visits to the UK in April 2018 (14% less than in April 2017), £2.0 billion in May 2018 (6% less than in May 2018) and £2.0 billion in June 2018 (11% less than in June 2017).
UK residents made 6.3 million visits overseas in April 2018 (1% fewer than in April 2017), 6.2 million visits overseas in May 2018 (3% more than in May 2017) and 7.4 million visits overseas in June 2018 (2% fewer than in June 2017).
UK residents spent £3.3 billion on visits overseas in April 2018 (7% less than in April 2017), £3.8 billion in May 2018 (16% more than in May 2017) and £4.5 billion in June 2018 (4% less than in June 2017).
For the sake of clarity, we should point out that the exchange rate is a factor in both the numbers holidaying in the UK where the post-Brexit fall in sterling benefitted incoming tourists and also in the number of migrant workers in the UK including in our NHS where the fall in sterling made working here less remunerative in euro terms than previously.
Frog in a tree