Bonus is located at ...
N51 BA.CEB
W1 BB.BDF
This is much closer to the fourth cache in this series than it is the first, so doing them in order will be beneficial.
You will need the answers from the six questions written in the four log books in the caches of this series.
Question 1 is written in the log book of cache #1 in this series and the answer gives you the number letter A in the above co-ordinates.
Question 2 is written in the log book of cache #2 in this series and the answer gives you the number for each of letter B in the above co-ordinates.
Question 3 is written in the log book of cache #3 in this series and the answer gives you the number for letter C in the above co-ordinates.
Questions 4, 5 and 6 are written on the back of the log in cache #4 in this series and the answers give you the numbers for letters D, E and F in the above co-ordinates.
Swag rules: please observe the unwritten-rule in the geocaching community that you only take a piece of swag if you put something of equal or better value/interest back into the cahe ... this doesn't apply to trackable items as these are obviously free to move as per their specified goal.
When you are approaching GZ, please be aware that unfortunately there are some old bits of barbed wire and off cuts of wire used for fencing in the area, so please mind where you tread and tread carefully.
Something to help you as you approach GZ ...
Following the obvious path heading south, GZ will be obscured by trees until you get close.
As the path bears east after a straight section, trees together numbering three may you see.
To reach GZ cross a carpet of Ivy.
To find GZ look for trees together numbering four not three.