Worse case scenario.
Rayner owned the house for eight years from 2007 and 2015 and made a capital gain of £48,500. It is not know if this number takes into account incidental costs of purchase, costs incurred in improving the asset and incidental costs of sale all of which would which would reduce the overal gain.
I’m assuming it was her principle private residence for three years until 2010 and that on marrying, she and her husband elected that his property to be considered their principle private residence for capital gains tax. They had two years to make the election. If they didn’t then HMRC would considered the case based on fact - where Rayner was spending most of her time.
If a dwelling-house has been used as its owner’s only or main residence at some time in his or her period of ownership, then the final part of the period of ownership will always qualify for relief.
The purpose of the final period exemption is to help the owner occupier who puts their house up for sale but cannot find a buyer
For disposals on or after 6 April 2014 but before 6 April 2020 the final period of ownership that qualifies for CG64985 relief was 18 months.
www.gov.uk/hmrc-internal-manuals/capital-gains-manual/cg64985
At most, Rayner has CGT to pay for three and half years out of eight - a net chargeable gain of £21,218 but remembering this may not include deductible expenses.
The annual CGT exemption for 2014/15 was £11,000 so assuming she had no other chargeable gains, then £10,218 is taxable. Treated at the top slice (any part of a taxable gain exceeding the upper limit of the income tax basic rate band (£31,865 for 2014/15) tax is charged at 28% = £2861. With interest and penalties say £3,000.
This is a matter for HMRC not the police. At worst she has been badly advised thinking that as this was the only property she owned then it was exempt from CGT not realising that getting married is not advantageous in this circumstance.