Hmm,
Firstly, I suspect the relatively slow 1Mb/s you achieve is due to distance from your exchange, however there are many factors that affect BB speed, no the 50 year old copper is not good but there are a few things worth trying:
You may like to try removing the master socket & connecting your router directly to the socket inside your master socket (nothing else connected) & doing a speed test, so if you have a noisy extension dragging the connection speed down then speed should/will improve.
Also you may consider disconnecting the bell wire, there are plenty of 'how to' if you google it, the bell wire can pick up interference and is now redundant.
Its regrettable that BT have the lions share of the broadband market in the UK, their organisation is clumsy, support is fairly abysmal & slow to respond (unless you're late paying) but generally their engineers are pretty good.
For a long time I suspected that BT changed the waveform of their ADSL I had so many clients who used them found their connection problematic or even disconnected until the router had its firmware updated.
If you cannot get fibre then perhaps look at some of the good quality providers, which in my opinion (having installed several hundred ISPs & various routers over the years) are:
IDNet - excellent
Zen Internet
AAISP - probably the best
Quite good are
Eclipse Internet
Plusnet
Demon
I do not work for any of the above organisations, the website thinkbroadband :: The UK's largest independent Broadband / ADSL troubleshooting website (incorporating news, reviews and comparisons)
will also help decide on your ISP.
The above comments my views from many years hands on sleeves up & other posters views & opinions may be different.
Bon chance
N