Pretty bowl! I have a dartington studio piece where the pontil mark has the blow pipes mark of Dartington on it. However I also have another piece where I was told it was Dartington by the seller and that has no mark. I have been thinking my other piece is perhaps Teign Valley glass (similar area, seller confused?). Dartington did do a range of studio pieces for a few years so it may be I guess?
Perhaps write to them and ask directly. I believe they are very helpful in responding ( note to self - write to Dartington).