Hi Tony, yes they are indeed Linnet (nice images btw). It would be very unusual to have Twite in the south west in August, and they are extremely rare at the res - just a handful of records in late October/November.
Hope this helps!

A walk around the Res this afternoon showed most of the species previously listed. Inc Wood and common Sandpiper, Ringed Plover, Weatear and what were probable the mystery Finches mentioned by Frankie Macrow.  I have added a link to a shot of one. I have nowhere near the expertise of some others so I will leave it to them to give a positive ID.  In my opinion (and reading my guide book) it would have a more pure white to rear and below tail if it was a Twite ? There were also lots of migrating Swallows and a few martins stopping for a rest, wash and a drink.

https://flic.kr/p/2jx17sX
https://flic.kr/p/2jx17r4
https://flic.kr/p/2jwXcRA
https://flic.kr/p/2jwWKBw
https://flic.kr/p/2jx2cM3

One Wood Sand and one Common Sand on the exposed area near the yacht club this morning.

Cheddar reservoir this afternoon - dunlin, sanderling and ringed plover at Cheddar End, 5 common sand and 2 wheatear around SW corner and the wood sand still at Axbridge end. Also 3 mystery finches at the Cheddar end. Probably linnets but looked and sounded rather like twite, hard to see in driving rain and didn’t see them for long

Wood sand, common tern, dunlin, sanderling, ringed plover, turnstone, wheatear and common sand this morning. Hooray for low water levels, boo to dogs off leads and photographers who get too close and flush everything

Still showing well at 5.30 pm

Reported by Dan Watson bird still near boat club Axbridge side 12:00 today