Fill the sink with hand hot water and a mild detergent. Put Jersey in sink/bowl, give it a good kneading gently rub areas where there is a high level of grime/staining, e.g. cuffs and collar. Knead a bit more and then leave it to soak.
Empty water and gently press water out of Jersey, add fresh water and knead again, repeat the empty water/gently pressing out of water/add fresh water until water runs clean.
When water runs clear carefully press water out of the Jersey without wringing which may cause it to become misshapen. When majority of water is removed lay the Jersey on a large towel and reshape. fold towel in and over the Jersey and roll up. Gently squeeze the roll through it's length to transfer the water from the Jersey to the towel. You will probably need to repeat with another dry towel if the Jersey is very heavy.
When damp reshape the Jersey again and lay on a flat bed airer or over a radiator with a towel underneath.
It sounds a faff but isn't really that bad.