About the 20p:
The original reverse of the coin, designed by William Gardner, and used from 1982 to 2008, is a crowned Tudor rose, with the numeral "20" below the rose, and TWENTY PENCE above the rose. To date, three different obverses have been used. On coins minted before the 2008 redesign, the inscription is ELIZABETH II D.G.REG.F.D. Coins minted after the 2008 redesign also have the year of minting on the obverse.
Like all the new decimal coins introduced in 1971, until 1984 the portrait of Queen Elizabeth II by Arnold Machin appeared on the obverse, in which the Queen wears the 'Girls of Great Britain and Ireland' Tiara.
Between 1985 and 1997 the portrait by Raphael Maklouf was used, in which the Queen wears the George IV State Diadem.From 1998 to 2015 the portrait by Ian Rank-Broadley was used, again featuring the tiara, with a signature-mark IRB below the portrait.
As of June 2015, coins bearing the portrait by Jody Clark have been seen in circulation.
In August 2005 the Royal Mint launched a competition to find new reverse designs for all circulating coins apart from the £2 coin. The winner, announced in April 2008, was Matthew Dent, whose designs were gradually introduced into the circulating British coinage from mid-2008. The designs for the 1p, 2p, 5p, 10p, 20p and 50p coins depict sections of the Royal Shield that form the whole shield when placed together. The shield in its entirety is featured on the £1 coin. The 20p coin depicts the meeting point of the second and fourth quarter of the shield, showing the lions rampant of Scotland and the lions passant of England. The date no longer appears on the reverse of the coin, and has instead been added to the obverse, where the lettering has been adjusted so as to fit the date in. Credit wikipedia.org/wiki/Twenty_pence_(British_coin)
20p Twenty Pence Shield 2012 - Circulated
Issued TBC Diameter 21.4mm Weight 5.00g Thickness 1.7mm Composition Cupro-nickel
(84% copper, 16%
Portrait of Her Majesty the Queen
1982-1984 Arnold Machin
1985- 1997 Raphael Maklouf
1998-2015 - Ian Rank-Broadley FRBS
2015 to date - Jody Clark
1982-2008 - William Gardener
2008 - Matthew Dent
Edge Plain Mintage *TBC