The current bobbin number for your model 19-E is #401 17 70. They fit bobbin case #411 49 62-01.
This place sells a pack of 10 bobbins for $8.95.
http://sewingmachine221sale.bizland....re/page46.html
This place has them at $1.15 each ($11.50 for 10)
http://sewing-machine-parts-store.co...brand=&page=27
I'm sure you can find more if you don't like these.
ETA: The second one does not ship abroad. Sorry. The first one is unclear about their rates, but I believe they will ship to the UK. If not, and you can't find a retailer who will, PM me and we'll work something out. I, too, have an older (mid-80's) Viking.