late 18th or early 19th century English saucer ID maker please

Not sure if this tea bowl saucer I have is possibly by Newhall, Spode or even possibly Keeling.
I have not been able to find another saucer exactly the same over the few years I have had it.

It is white ground, with a deep pink trim with pink floral design to the interior rim and a floral design at the centre.
The saucer has a swirling fluted rim. It is marked on the base 158 and is 13.5cm in diameter.

Any help would be appreciated in the ID of the maker or any pointers in the right direction.

New Hall and Keeling are probably your best bet, and it often comes down to the fineness/delicateness of the decoration since they all copied each others designs. This is particularly fine so I'd say New Hall. The number on the back is the pattern number. It would have helped if it had an N in front for New Hall. There is a book of patterns by the different factories. I'll look up the title .

I already found out after posting this it is not a Keeling pattern, as their pattern 158 is totally different. It is probably New Hall, but to date I have been unable find another. Thank you for your help again.

Found the book, unfortunately it's a bit expensive - 'A Guide to New Hall Porcelain' by A de Saye Hutton
My only concern is the number is not as fine as the decoration, which could point to one of New Hall and Keeling's contemporaries.

Thanks for the name of the book, I will look in to it.

I was also thinking it may have been one of the other factories, but which one! The number is not painted how I would normally see it on other New Hall pieces, I was wondering about Spode, but again, the number does not seem to match how their numbers are on items.

I feel this one will remain a mystery.

Thank you for your help and input.