A Robert W Heaven. In 1911 he is referred to as William. And the 1911 Census states they were married in 1886. Calculated date. The form asks for years married.

To be pedantic a Robert Heaven married in 1882. It may be a different Robert Heaven. Because in the 1901 Census a Sarah Heaven from Meifod is living with a Robert Heaven in Cheshire.

Matilda Winifred Baskerville Heaven birth was registered in the first quarter of 1885 in Oswestry registration district.

Robert was buried on 12 March 1884, so the parish register concords with the date of death. In the 1881 Census he was single and living in Meifod. He married Sarah Davies on 22 March 1882 in Meifod.

Surnames as middle names was certainly a thing. Low single digit percentages of births is my guess based on my Australian experience. Maybe slightly less common for girls than boys.

Baskerville might be a middle name. I’ve been thrown by that before. Doesn’t explain the date though.

I might try and genealogy it later

You might be surprised how often headstones have incorrect dates, I mostly have seen year issues, but also have seen month and day issues. I haven’t personally come across incorrect names or relationships before but it would not surprise me.