Consideration (UK)

Are the following agreements legally binding??

1. Henry asked Mary to sweep his lawn. After Mary had done so, Henry was so delighted with her work he promised to pay her 150.

2.Ben agreed to sell his vintage Harley Davidson to Roger for 10.

3.Arsenal F.C agreed to pay London Metropolitan Police an extra 50,000 if they provided riot police with full body armour and riot shields for their home fixture against Chelsea in the Premiership match as they feared that there would be serious trouble.

4. Charlie agreed to refurbish a block of flats for Alan by a deadline of June 28th. Alan agreed to pay Charlie 10,000. Charlie started the work, then decided that he needed more money to hire more builders to complete on time. Alan agreed. Charlie hired more builders and finished on 28^th June. Alan refused to pay the extra money.