"….For a ha'p'orth of tar." (Ha'p'orth = half pennyworth.) This is an old nautical saying, once in common use but now quite rare. Essentially it means that if you have done a good, complex job on something (eg you have almost finished repairing your ship) you should keep up the same high standards right to the end, and finish everything properly (the ship won't be properly watertight without tar.)
The saying makes perfect sense if you think how easy it is, when you've been working on something for a long time, to get to a point where you think, "That's it, I've had enough" and rush the last stages. The more common saying, "If a job's worth doing, it's worth doing well" has a similar idea but is less specific. There is also a poem beginning "For want of a nail, the shoe was lost, for want of a shoe the horse was lost…" which goes on to describe a complete disaster, all caused by someone failing to provide a horseshoe nail.
The saying makes perfect sense if you think how easy it is, when you've been working on something for a long time, to get to a point where you think, "That's it, I've had enough" and rush the last stages. The more common saying, "If a job's worth doing, it's worth doing well" has a similar idea but is less specific. There is also a poem beginning "For want of a nail, the shoe was lost, for want of a shoe the horse was lost…" which goes on to describe a complete disaster, all caused by someone failing to provide a horseshoe nail.
