G6Bob:
Thanks for the help guys, I am happy with the example situation I posted asking about… Much appreciated 
Reading some of the responses, I am unclear about the “Two reduced rests” in the one week…
If I have a reduced rest of 24 hours mid week, followed by 27 at the end of the week, I understand now this constitutes as a reduced rest, I am unsure about the pay back procedure. Does the second rest period pay back the first rest period, or would I have to pay bay one of them (i.e 21 or 18 hours) back? if so which one?
The second period doesn’t pay back the first, after the payback it wouldn’t leave enough hours for it to even be a daily rest. Compensation must be attached to a rest period of at least 9 hours and in that scenario taking 21 hours as compensation leaves only 6 hours. In a situation were less compensation was required it could be used that way. However, if the compensation reduces the period to less than 24 hours then it would no longer be a weekly rest and wouldn’t reset the 144 hour clock.
You can compensate either rest period, doesn’t matter which. Probably easiest to do the one that needs the least compensation.
G6Bob:
Also If I have a rest period on
Week one of 40 hours,
Week two of 45 hours,
Week three 39 hours,
Week four 50 hours,
Week one reduced by 5 hours, and paid back in full (Attached to a 45 hour rest period) by the end of week four, with another reduced rest in week three… Is this a legal example or Can I not reduce again until I have paid back in full my reducer in week one?
That’s legal, with one small caveat. Technically the compensation must be paid back by the end of the third week following the reduction. The end of the third week following would be at midnight on the Sunday so, by the letter of the regulations, you should have to have completed the 50 hours by then but I don’t think that is policed too strictly. For instance, I have never seen any of the analysis software flag an infringement if the compensation isn’t completed before midnight.
The 39 hours in week 3 will need paying back before the end of week 6 and you could reduce again in week 5, before that compensation is made, if you wished.
If you had a daily rest of at least 14 hours before the end of week 4 your then your 5 hours will have been compensated for, provided you had a reduced break available to add the 5 hours to. If you did have a reduced available a daily rest of between 14 and 16 hours will take care of that. Sixteen+ hours and it’s done as well by adding it to a regular daily rest.