You'll need to clarify with your MO, not confused.com!
Assuming its the same GR10 that I know of, (see CAP747), it relates to certification of painting jobs. If that is the case, then that really is taking the p***.
It may possibly include the paint-work task itself, but you dont say the content of the annual, or any paint-job you had.
The Annual should have been done to a specific Maintenance Program or to CAA/LAMP/A/2007/1 for acceptance into the Part M regime. LAMS is deemed not suitable for EASA types. Whilst your in CAP747, see GR15 about this.
The one year ARC fee payable to the CAA will be about £80 for an Arrow.
Definitely get this clarified with the MO.