Just having a look at this 1 bed flat in North Watford marketed by the folks at Taylors.Balmoral Rd - Letting Agents in Watford
Assuming you can achieve around £800 per month for the flat you would be looking at a 5.6% yield which is very good!
Check out the full description on Rigthmove here: 1 Bed Flat – Balmoral Rd
The photos make it look a little bit cluttered but I think but once you de-clutter  and get some professional pics taken I think the flat would rent very quickly.
Balmoral 1 bed b
Although the description says ideal for commuters this one is a good 20 minute walk to Watford Junction and in my experience over 15 minutes will put a number of commuters off.  Something to consider.
On the flip side of that, its a nice road to live on and the M1/M25 are VERY accessible from here so a bonus for anyone needing good motorway connections.
Not a bad option at all in my humble opinion.