Bring vinegar to a boil in a medium saucepan. Remove from heat and add mustard seeds. Cover and let stand at room temperature until seeds have absorbed most of the moisture, about 1-1/2 hours.

Prepare boiling water canner. Heat jars in simmering water until ready for use. Do not boil. Wash lids in warm soapy water and set bands aside.

Combine mustard seeds and liquid, water and Worcestershire sauce in a food processor or blender. Process until slightly grainy. Add cranberries and blend until chopped.

Bring cranberry mixture to a boil in a medium saucepan, stirring constantly. Reduce heat and simmer for 5 minutes, stirring frequently. Whisk in sugar, dry mustard and allspice. Continue to simmer, stirring frequently, until volume is reduced by a third, about 15 minutes.

Ladle hot mustard into a hot jar leaving a 1/4 inch headspace. Remove air bubbles. Wipe jar rim. Center lid on jar and apply band, adjust to fingertip tight. Place jar in boiling-water canner. Repeat until all jars are filled.

Water must cover jars by 1 inch. Adjust heat to medium-high, cover canner, and bring water to a rolling boil. Process quarter pint jars for 10 minutes, adjusting for altitude. Turn off heat and remove cover. Let jars cool 5 minutes. Remove jars from canner; do not retighten bands if loose. Cool 12-24 hours. Check lids for seal, they should not flex when center is pressed.