Historic rent charge

Sarlo

I have lived in my property for 20 years and am going through the selling process. The purchasers solicitor have said there is a historic rent charge against the property of £3 a year, drawn up in 1926. I wasn’t aware of this and it has never been collected. The solicitor has taken out an indemnity insurance but needs to check with the mortgage lender that it is suitable. I’m getting nervous now as it’s been 2 days and still no word. I know rent charges can be a pain but as it’s 20 years surely the likelihood of someone resurrecting it is unlikely? Also, I have read it may be classed as extinguished after 12 years? Any insight greatly appreciated - I can’t deal with another restless night!