IIRC BT have already trialled it (Bournemouth is an exchange which took part in the first trial).
That's because they've run out of numbers in that code and will have started to use 0 or 1 as the start of the local number, meaning the exchange can't tell if you're doing local dialling, dialling a short code (eg. 17070), or an STD code without applying a timeout.
eg. a number like 01202 123456 or 01202 012020.
There have been "shadow" numbers with local parts starting with 0 and 1 since the 1990s at least, eg. 0161-0xx xxxx, usually used as the physical destinations of 0800 or similar numbers.