There will be two joke prizes replacing the £1 and £50. These joke prizes will be roughly worth the values they replace. However, there will be a square called the "Joke Prize Monster", replacing the £5,000, activated by 4 randomly selected boxes. If selected in the correct boxes, will replace the joke prizes with values ranging from £250 to £25,000. The correct boxes that will activate the Joke Prize Monster will be revealed after the box containg the Joke Prize Monster is opened. This can only be activated before 2-box, and if you select If the Joke Prize Monster is in your box, you win £5,000. If you choose the JPM box after both joke prizes have been removed, nothing is changed.
I have a few more special squares in my series. Some of them are outrageous though.