Thanks Beth. A engineer came out and discovered a cable fault in the in-home cables, and hopefully I haven't noticed problems since.
But it was virginmedia tests that discovered a fault with the in-home cabling.
Just as a note: I was having issues downloading backup phone data from Google UK servers to my phone via wireless, that led to finding such fault. Also still having, or last time I tried, issues downloading such data from Google servers. Google state it ain't them. Samsung details it ain't them. Thus that leaves WiFi or virginmedia broadband. WiFi I doubt, as I'm within 1 to 2 meters away from WiFi router and am using a flagship phone from Samsung.