National Grid shares rights issue - tail swallowing

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In the recent National Grid shares rights issue, they offer a scheme to a shareholder whereby some of the rights to buy new shares are sold, and the proceeds used to subscribe for new shares in the remaining rights. It is sometimes called tail-swallowing.

Does selling transaction in this tail-swallowing scheme count as a disposal for CGT purposes?

A simple interpretation of the rule is that you are selling rights and buying shares. These two things are not the same, so the selling has to count as a disposal.

My googling found https://www.treasurers.org/ACTmedia/shareissuing.pdf from 25 years ago, which says on page 15:
"The MMC also recommended that the CGT rules be amended so that “tail-swallowing” s not treated as a disposal and HM Treasury invited representations on this issue."
indicating that in years gone by tail-swallowing was counted as a disposal. Perhaps things have changed.