1920 UK Penny - Die Error?

Are you talking about the coin having a woodie appearance or the missing portions of some letters?
I think the woodie appearance was caused by a less than fully mixed metal content that were used in the creation of the planchet.
The missing portions of some letters might be Grease Filled Dies, but I am leaning toward wear.

I agree that the mark on the obverse looks like tape.

This is a typical average circulated early George V penny such as could still be found in everyday circulation up to February 1971. The obverse of these coins is usually in better condition than the reverse, partly because it had a higher rim. The coin exhibits 'ghosting', which is very common on 1911 - 1926 UK pennies: you can see a faint outline of King George V's head around Britannia on the reverse.

The stick as you wish to call it is an illusion caused by the streaks.
It is too worn to be removed lustre which may of left a different tone (although not that colour) and impossible to remove the bronze its solid not coated.
I mean tape as been put on the coin in later years and when taken off has left some on the coin.
Yes the letters to the reverse are just worn.

Thanks for all you help and replies. I have decided to nickname my coin 'My 1920 Sellotape Head, Broken Stick - Ghosting' penny.