Watch List notes:

Charles I (1625-49), Civil War coinage, 1642-49, Oxford mint, 1642-46, Unite, 8.79g, 1644, i.m. plume with bands on obverse, CAROLVS . D:G: MAG: BR: FR: ET. HI: REX, crowned and draped bust with falling lace collar left, breaking inner circle, holding sword and left curving olive branch, value XX behind, rev. diamond stops, legend and declaration in continuous scroll, EXVRGAT. DEVS. DISSIPENTVR. INIMICI. RELIG. PRO. / .LEG: ANGL / LIB. PAR. / .1644. / .OX. , three small plumes above (BJ dies IX/16; North 2389; SCBI 33 (Brooker) 852A same dies; Schneider 323 same dies; S.2735A), double struck below the bust, the die not properly prepared on the reverse so some raised lines clearly visible, a skillfull repair around the initial mark plume, very fine, very rare.
A search on coinarchives shows that only one other example has been offered in the last twenty years.
Estimate: £8,000 - £10,000