i wouldnt have thought such a massive arb opportunity would...

i wouldnt have thought such a massive arb opportunity would present itself. i think you may have misinterpreted the info..the ex date is the important date, as opposed to the record date

Gloucester Shares trade 'ex' entitlement to Capital Return and
Special Dividend
10.00am on Monday, 18 June 2012
Record date for Capital Return and Special Dividend (i.e. the
Capital Return Record Date): time and date for determining
entitlements to the Capital Return and Special Dividend
7.00pm on Friday, 22 June 2012