In my area, in the early 1980's it was quite rare here to see a named loco of any type, so I used to try to buy unnamed locos, but unnamed locos tended to be rare due to the popularity of names with the buying public and the manufacturers wanting the most popular models that would sell. It is nice to have a name, but my class 37's and 47's having over half named just to try not to duplicate numbers, it was hard to find what I wanted off the shelf. When I did I sometimes bought two so I could later renumber one, as one never knew if the livery would come back round again. Some will need repainting as I have locos with the orange roof stripe which I model before this came in. (All locos on the rail network in the UK have to have the orange roof (Sometimes lower) stripe. It is to remind staff not to climb higher in case of overhead electric, and are fitted to all locos even if they never work in overhead areas. Not sure when it came in, but I know it wasn't there in the Western Region in Wales in the early 1980's).
I have the odd large logo locomotive which only just fits in my time period as the Western Region (Certainly in South Wales) were slower then the other regions to adopt new liveries. Sometimes up to 10 years behind still repainting in old liveries at local depots!
The few locos that worked services into London and back were the exception to this so our HST's tended to be the first to change livery a long time before the rest. In this way, I found my local area to be so much easier to obtain suitable stock to run.