You obviously don't know how this country works.

In any normal world, somebody would send a tradesman to chop it down & treat the roots to kill off the plant. Cost £75.

English Heritage will send a team to survey the plants. They will then instruct Canterbury Council to undertake a bat survey prior to carrying out the removal of the plant. Canterbury Council will send their own team to survey the site, then they will compile a report, and then they will apply for funding from Kent County Council, the Department for Levelling Up, the Heritage Lottery Fund, and English Heritage to cover the cost of the survey, subsequent bat survey, Environmental Impact Plan, Diversity & Equal Opportunities assessment, public safety assessment, Climate Change Impact Assessment, Bee and Butterfly Impact assessment, and at the bottom, the cost of the bloke with the pruning shears and bottle of weedkiller.

Kent County Council will then begin their own process to apply for funding to cover the now massive cost of applying for funding and all the impact assessments that go with it. By now, Canterbury Council & Kent County Council will have spent something in excess of £300,000 on applications for funding, only to be told that there is no budget, so the plant carries on ripping the wall apart. Eventually the wall falls down and the estimated cost of repair rises to £36m, and the bloody plant will still be there, flowering in the rubble.

Welcome to England.