Virgin Lightning at 300 Mbps
Once upon a time, circa 2:17pm on 23 April 2014, our house was connected to the Interweb with a strand of fiber optic cable.
We started with 200 Mbps, which was very nice.
A couple of years later, after we made an inquiry about cost, the Telco backspaced out the "200" and typed in "300" Mbps. And it was so.
Then, at some point where we failed to even notice, the Telco silently backspaced out the "300" and typed in "500" Mbps. They forgot to tell us. And we didn't even notice any difference, because FAST is nearly as fast as F-N-FAST.
None of this required anyone to visit our house (all equipment is inside, so we would have noticed).
A few weeks ago, after we made an inquiry about cost, they sent out a nice technician to install a new ONT and Router. He then clicked on "1.5 Gbps" and it was so.
Point being, once you have fiber optic connection, the sky is the limit. Ours will probably go to 10+ Gbps at some point, maybe.